The Catback Exhaust, Downpipe, and Manifold Thread.
As of 3/8/2012 this list is incomplete.
I invite all Elite members to edit this post for both accuracy and to include any and all relevant information. Extrapolation and expounding on covered topics is also an excellent idea, but anything more than a brief overview should be linked to a separate thread.
Seeing as there is no thread (that I can find) containing information on the various exhausts available for WRX/STI's, I thought I'd piece this together to help everyone out. All fitment needs to be double checked before ordering as in most cases there are multiple fitments available (i.e. hatch and sedan models). Prices gathered from various vendors, and are approximated. I will list all available cat-back exhausts, downpipes, and exhaust manifold's currently available both new and used.
For a detailed technical discussion, please visit The Exhaust Design and Exhaust Theory thread.
TBE = Turbo Back Exhaust (Includes Downpipe) *REQUIRES TUNE*
CBE = CatBack Exhaust (Does not include Downpipe)
OTS = Off the Shelf, usually referring to an AccessPort tune
Stage 1 = Basic Reflash of the computer, can be done totally stock or in addition to an intake
Stage 2 = Flash for the addition of a downpipe
Protune = A professional tune, which is superior to an OTS tune in regard to power, safety, and longevity. Research your choice in tuner extremely carefully.
Exhaust Manifold = Typically called a "header"
For best results, seek a full 3 inch turbo back exhaust.
Grinder34's take on exhausts (stolen from another thread):
As far as the axle-back (muffler, etc..) is concerned, its largely down to sound, look, and weight (if you're into that). There are LOTS of youtube videos you can find with different exhaust setups. As for the downpipe, most will serve you just fine. There are catted (emissions legal) and uncatted (usually illegal, but most states dont care except CA). The uncatted will usually net you a bit more performance, but only maybe butt-dyno noticeable. There are a ton of brands out there.
The one thing to take into account with the post-turbo exhaust, is that it's a true 3" all the way to the end. Some downpipes neck down to 2.5" which is an unnecessary restriction since most people end up with a 3".
So that's what most people think of when they talk "exhaust" but theres also some pre-turbo exhaust components: the header and up-pipe. There are definitely gains to be had there! Are you interested in those as well? If so, the first question you have to answer is: equal (EL) or un-equal length (UEL)? UEL is what the car comes with and is generally attributed to the "boxer rumble" you may have heard about. But UEL basically has exhaust pulses from each cylinder colliding with eachother and is probably not an ultimate-power type of setup. But it sounds fun. EL, on the other hand, has all the exhaust pulses equally distributed..but loses some of the traditional sound. For upgrading the header's performance, you dont have to swap the whole header out: there are some "cross-pipe" options, namely the GrimmSpeed cross-pipe that can give you some gains. You can also port and polish (PnP) the other OEM header components for some reasonable gains. I havent actually done that but its pretty widely accepted, from what i understand. The headers connect to the up-pipe (which goes up to the turbo). I dont actually know much about the OEM up-pipe, but there are lots of options for those as well. But you'll want to make sure before you buy anything that they all connect nicely: some are two-bolt, some are three-bolt, and the occasionaly v-band from what i remember.
To start, the cat back portion of the exhaust does not typically require a tune. That being said most people start off their modifying with an intake (tune required), a CBE, and an OTS stage 1 tune. Adding a downpipe also requires a tune, and can be done on it's own (no CBE or intake) with either an AP stage 2 tune, or a protune. If you are not currently using any type of flash device to tune the car or a have tuner to tune the car, it is imperative you do not do any modification that changes the airflow characteristics of the motor. Any time you add additional performance parts to the car it must be tuned for these new modifications. Certain exhausts are available as both a CBE and TBE, or as only one or the other. For that reason the "Type" column shows how it is available.
The CBE portion of your exhaust is the part that determines the majority of the sound, and has a very small (~3%) effect on performance. It will consist of the axle back portion as well as the midpipe. Most CBE's can be swapped for each other with no need to re-tune. You will want to re-tune however, when either the size of the piping or flow characteristics change drastically. Assuming all else being equal however, the CBE is primarily for personal preference of both sound and aesthetics. For the GR they come in various styles including single exit, dual exit, dual exit quad tipped, angled exit(s), stainless tips, or even burnt titanium tips (personal favorite) all of which range in price and volume. To be added upon relative completion of this list will be approximate decibel ratings.
GD WRX/STI 2004-2007 Exhausts
Downpipes
A downpipe is the portion of the exhaust the portion where the most power can be gained, or at least initially in a car that is mostly stock form. This piece connects the hotside of the turbo to the midpipe, and replaces the extremely restrictive stock 2.5 inch downpipe. They will come both with and without catalytic converters. In most states you will NOT pass emissions without a catalytic converter. The downside of having a cat however is that sooner or later it will need to be replaced, and that (according to some) it can at times make less power than having a catless downpipe instead.
The term "stage 2" will typically refer to a modified car with a full turbo-back exhaust. Subaru's offer two different types of after market downpipes, the bellmouth which is a downpipe with a oval shaped opening that is open to all the exhaust from the turbo and the divorced which has a similar opening to the bellmouth but incorporates a metal piece to separate the exhaust gasses coming from the wastgate and the turbo itself. For a detailed explanation on the differences between various types/sizes/materials used, please see this thread here.
GR WRX/STI 2008-2012 Downpipes
GD WRX/STI 2002-2007 Downpipes
Exhaust Manifolds, or "Headers".
As of 3/8/2012 this list is incomplete.
I invite all Elite members to edit this post for both accuracy and to include any and all relevant information. Extrapolation and expounding on covered topics is also an excellent idea, but anything more than a brief overview should be linked to a separate thread.
Seeing as there is no thread (that I can find) containing information on the various exhausts available for WRX/STI's, I thought I'd piece this together to help everyone out. All fitment needs to be double checked before ordering as in most cases there are multiple fitments available (i.e. hatch and sedan models). Prices gathered from various vendors, and are approximated. I will list all available cat-back exhausts, downpipes, and exhaust manifold's currently available both new and used.
For a detailed technical discussion, please visit The Exhaust Design and Exhaust Theory thread.
TBE = Turbo Back Exhaust (Includes Downpipe) *REQUIRES TUNE*
CBE = CatBack Exhaust (Does not include Downpipe)
OTS = Off the Shelf, usually referring to an AccessPort tune
Stage 1 = Basic Reflash of the computer, can be done totally stock or in addition to an intake
Stage 2 = Flash for the addition of a downpipe
Protune = A professional tune, which is superior to an OTS tune in regard to power, safety, and longevity. Research your choice in tuner extremely carefully.
Exhaust Manifold = Typically called a "header"
For best results, seek a full 3 inch turbo back exhaust.
Grinder34's take on exhausts (stolen from another thread):
As far as the axle-back (muffler, etc..) is concerned, its largely down to sound, look, and weight (if you're into that). There are LOTS of youtube videos you can find with different exhaust setups. As for the downpipe, most will serve you just fine. There are catted (emissions legal) and uncatted (usually illegal, but most states dont care except CA). The uncatted will usually net you a bit more performance, but only maybe butt-dyno noticeable. There are a ton of brands out there.
The one thing to take into account with the post-turbo exhaust, is that it's a true 3" all the way to the end. Some downpipes neck down to 2.5" which is an unnecessary restriction since most people end up with a 3".
So that's what most people think of when they talk "exhaust" but theres also some pre-turbo exhaust components: the header and up-pipe. There are definitely gains to be had there! Are you interested in those as well? If so, the first question you have to answer is: equal (EL) or un-equal length (UEL)? UEL is what the car comes with and is generally attributed to the "boxer rumble" you may have heard about. But UEL basically has exhaust pulses from each cylinder colliding with eachother and is probably not an ultimate-power type of setup. But it sounds fun. EL, on the other hand, has all the exhaust pulses equally distributed..but loses some of the traditional sound. For upgrading the header's performance, you dont have to swap the whole header out: there are some "cross-pipe" options, namely the GrimmSpeed cross-pipe that can give you some gains. You can also port and polish (PnP) the other OEM header components for some reasonable gains. I havent actually done that but its pretty widely accepted, from what i understand. The headers connect to the up-pipe (which goes up to the turbo). I dont actually know much about the OEM up-pipe, but there are lots of options for those as well. But you'll want to make sure before you buy anything that they all connect nicely: some are two-bolt, some are three-bolt, and the occasionaly v-band from what i remember.
Catalytic converter back Exhausts, or Catbacks.
To start, the cat back portion of the exhaust does not typically require a tune. That being said most people start off their modifying with an intake (tune required), a CBE, and an OTS stage 1 tune. Adding a downpipe also requires a tune, and can be done on it's own (no CBE or intake) with either an AP stage 2 tune, or a protune. If you are not currently using any type of flash device to tune the car or a have tuner to tune the car, it is imperative you do not do any modification that changes the airflow characteristics of the motor. Any time you add additional performance parts to the car it must be tuned for these new modifications. Certain exhausts are available as both a CBE and TBE, or as only one or the other. For that reason the "Type" column shows how it is available.
The CBE portion of your exhaust is the part that determines the majority of the sound, and has a very small (~3%) effect on performance. It will consist of the axle back portion as well as the midpipe. Most CBE's can be swapped for each other with no need to re-tune. You will want to re-tune however, when either the size of the piping or flow characteristics change drastically. Assuming all else being equal however, the CBE is primarily for personal preference of both sound and aesthetics. For the GR they come in various styles including single exit, dual exit, dual exit quad tipped, angled exit(s), stainless tips, or even burnt titanium tips (personal favorite) all of which range in price and volume. To be added upon relative completion of this list will be approximate decibel ratings.
GR WRX/STI 2008 - 2012 Exhausts
| Model | Type | Cost |
| Agency Power SS | CBE | $750.00 |
| Agency Power Ti | CBE | $850.00 |
| AMR | TBE* | $1,900.00 |
| Apexi Megaphone | CBE | $650.00 |
| ARK Performance | CBE/TBE* | $950.00 (CBE) $1,500.00 (TBE) |
| Blitz Nut Spec R | TBE* | $2,000.00 |
| Borla | CBE | $925.00 |
| CNT Performance | CBE/TBE* | $350.00 (CBE) $700.00 (TBE) |
| COBB | CBE | $1,200.00 |
| Crawford | CBE | $750.00 |
| Crawford Gymkhana | CBE | $400.00 |
| Fast Motorsports | CBE | $340.00 |
| Fujibitsu | CBE | $900.00 |
| Greddy Spectrum Elite | CBE | $1,500.00 |
| HKS ES | TBE* | $1,750.00 |
| HKS Legmax | TBE* | $2,000.00 |
| Invidia Q300 | CBE | $850.00 (Stainless Tip) $975.00 (Titanium Tip) |
| Invidia N1 | CBE | $725.00 (Stainless Tip) $900.00 (Titanium Tip) |
| Lachute Performance | CBE/TBE* | $1,500.00 (CBE) $1,800.00 (TBE) |
| Magnaflow | CBE | $900.00 |
| Miltek | TBE* | $1,850.00 |
| Nameless | CBE | $1,200.00 |
| P&L | CBE | $1,000.00 (Cannister or Quad Tip) |
| Perrin Single Tip | CBE | $1,000.00 |
| Perrin Quad Tip | CBE | $1,200.00 |
| SPT | CBE | $900.00 |
| Turbo XS | CBE | $715.00 |
| Turbo XS | TBE* | $1,120.00 |
| Ultimate Racing | CBE | $750.00 |
GD WRX/STI 2004-2007 Exhausts
| Model | Type | Cost |
| AMS | CBE | $640.00 |
| Apexi GT Spec | CBE | $900.00 |
| Apexi N1" | CBE | $700.00 |
| Blitz Nur Spec R | CBE | $680.00 |
| Blitz Nur Spec R Touring | CBE | $800.00 |
| Borla Hush | CBE | $640.00 |
| Borla XR-1 | CBE | $665.00 |
| BPM GT | CBE | |
| BPM Twister II | CBE | |
| Buddy Club Spec III | CBE | |
| Cobb 3" | CBE | |
| Crawford | CBE | |
| Crawford Gymkhana | CBE | |
| Fujitsubo Legalis | CBE | |
| Fujitsubo Power Getter | CBE | |
| Fujitsubo RM01A | CBE | |
| Greddy Evo/Evo 2 | CBE | |
| Greddy Sp2 | CBE | |
| Greddy TI | CBE | |
| Helix Titanium | CBE | |
| HKS Carbon TI | CBE | |
| Invidia G200 | CBE | |
| Invidia N1 Race/Street | CBE | |
| JIC 505S | CBE | |
| MadDad Whisper | CBE | |
| Megan Racing | CBE | |
| Perrin | CBE | |
| Prodrive | CBE | |
| RS*R | CBE | |
| SPT | CBE | |
| Tanabe Medallion | CBE | |
| Turbro XS | CBE | |
| Turbo XS RFL-Ti | CBE |
Downpipes
A downpipe is the portion of the exhaust the portion where the most power can be gained, or at least initially in a car that is mostly stock form. This piece connects the hotside of the turbo to the midpipe, and replaces the extremely restrictive stock 2.5 inch downpipe. They will come both with and without catalytic converters. In most states you will NOT pass emissions without a catalytic converter. The downside of having a cat however is that sooner or later it will need to be replaced, and that (according to some) it can at times make less power than having a catless downpipe instead.
The term "stage 2" will typically refer to a modified car with a full turbo-back exhaust. Subaru's offer two different types of after market downpipes, the bellmouth which is a downpipe with a oval shaped opening that is open to all the exhaust from the turbo and the divorced which has a similar opening to the bellmouth but incorporates a metal piece to separate the exhaust gasses coming from the wastgate and the turbo itself. For a detailed explanation on the differences between various types/sizes/materials used, please see this thread here.
GR WRX/STI 2008-2012 Downpipes
| Model | Catalytic Converter | Material | Width | Cost |
| Cobb Catted Bellmouth | Yes | 304 Stainless | 3 Inches - Tapered to 2.5 - No Flex Joint | $600.00 |
| Injen Divorced V1 | Yes | 304 Stainless | 3 Inches - No Taper/Flex Joint | $550.00 |
| Injen Divorced | No | 304 Stainless | 3 Inches - No Taper/Flex Joint | $420.00 |
| Invidia Divorced V1 | Yes | 304 Stainless | 3 Inches - No Taper/Flex Joint | $500.00 |
| Invidia Catless Divorced | $300.00 | |||
| Invidia Catless Bellmouth | $250.00 | |||
| Nameless Performance | $600.00 | |||
| Tomei Expreme Catless Bellmouth | $375.00 | |||
| TurboXS Catless Bellmouth | $315.00 |
GD WRX/STI 2002-2007 Downpipes
| Model | Catalytic Converter | Material | Width | Cost |
| Cobb Bellmouth | Yes | 304 Stainless | 3 Inches - Tapered to 2.5 - No Flex Joint | $600.00 |
| HKS Bellmouth | No | 304 Stainless | 3 Inches - No taper/Flex Joint | $450.00 |
| Injen Bellmouth | Yes | 304 Stainless | 3 Inches - No taper/Flex Joint | $550.00 |
| Invidia Divorced | Yes | 304 Stainless | 3 Inches - No Taper/Flex Joint | $500.00 |
| Invidia Bellmouth | No | 304 Stainless | 3 Inches - No Taper/Flex Joint | $250.00 |
| Invidia V2 Bellmouth | No | 304 Stainless | 3 Inches - No Taper/Flex Joint - 2 O2 Bungs | $275.00 |
| Invidia V3 Divorced | No | 304 Stainless | 3 Inches - No Taper/Flex Joint | $290.00 |
| Turbo XS Bellmouth | No | 304 Stainless | 4 Inch Bellmouth to 3 Inch Piping - No Flex Joint | $315.00 |
Exhaust Manifolds, or "Headers".
As almost all manifolds fit model years 2002-2012, this will be a one chart section. As such, confirm all fitment before purchasing as there may be minor differences for each manifold across the model years. Additionally, a considerable amount of manifolds include their own up-pipe section. I will include a column at the end to note if said manifold includes this piece. Additional information on up pipes can be found below this section.
The reason Subaru's (specifically FI models) have the trademark "rumble" is the design of the exhaust manifold. The uneven "pulses" from the pistons creates this effect. Manifolds are a highly detailed and technical subject and the debate between UEL and EL continues to rage on, but the general accepted truths are that an equal length manifold will have a much more even pulse distribution and shorter primaries to the collectors. Because of this, EL manifolds will typically nets larger gains, faster throttle response, quicker spool, and more top end power. The trademark "Boxer Rumble" however is no longer as present, and as such many individuals continue to run an UEL manifold to preserve the iconic sound. High horsepower cars can and do continue to be built using UEL, but often at a sacrifice of power as compared to EL.
The reason Subaru's (specifically FI models) have the trademark "rumble" is the design of the exhaust manifold. The uneven "pulses" from the pistons creates this effect. Manifolds are a highly detailed and technical subject and the debate between UEL and EL continues to rage on, but the general accepted truths are that an equal length manifold will have a much more even pulse distribution and shorter primaries to the collectors. Because of this, EL manifolds will typically nets larger gains, faster throttle response, quicker spool, and more top end power. The trademark "Boxer Rumble" however is no longer as present, and as such many individuals continue to run an UEL manifold to preserve the iconic sound. High horsepower cars can and do continue to be built using UEL, but often at a sacrifice of power as compared to EL.
WRX/STI 2002-2012 Exhaust Manifolds
| Model | Features | Runners | Cost | Includes Up-Pipe |
| ETS Equal Length | 2.0 Diameter Big Turbo, 1.5 Diameter Stock. 2 Bolt Up-Pipe connection | Equal Length | $850.00 | No |
| GTSpec | 45mm Primaries, 304 Stainless Steel. 3 Bolt Up-Pipe connection | Both Equal and Unequal | $630.00 | Yes |
| HKS | 42mm Primaries, 409 Stainless Steel | Equal Length | $630.00 | No |
| HKS | 304 Stainless Steel. 2 Bolt Up-Pipe connection | Unequal Length | $1,250.00 | No |
| Invidia | 304 Stainless Steel | Equal Length | $1,025.00 | Incorporated |
| Invidia Big Piping | 38mm-49mm Primaries, 304 Stainless Steel | Equal Length | $1,025.00 | Incorporated |
| Invidia Race | 42mm Primaries, 304 Stainless Steel | Equal Length | $875.00 | No |
| KillerB Holy Header | 321 Stainless Steel - Full Review Here | Equal Length | $1,400.00 | No |
| LiteSpeed | 304 Stainless Steel - Dyno Results Here | Unequal Length | $700.00 | No |
| Nameless Equal Length | *Not Yet Released | Equal Length | *Not Yet Released | *Not Yet Released |
| Tomei Equal Length | 304 Stainless Steel with a 3 Bolt Up-Pipe connection. 4-2-1 Design with 42.7mm-45mm-60mm. | Equal and Unequal Length | $750.00 | Yes |
Note: A variety of sources were used in the making of this post and while nothing has been directly copied, it can be stated that all information posted has a verifiable basis in fact and is not speculation. The moderators and ElitSTI team have/will continue to monitor this post for as much accuracy and foundation in fact as possible.
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