OBX Exhaust Experiences

[mijophil]

Well I recently made my first post in the new member section and am now coming here to see if anyone has experience with OBX exhaust on their fifth gen. I see two different systems (2" OD piping and 3" OD piping).

 

I'm mainly looking to go stage 2 with probably a road tune, and from my understanding, it's best/required to be fitted with a new downpipe and/or catback. I'm looking for the benefits of being stage 2 while keeping as close to stock sound as possible. Am I correct in thinking the 3" OD will be louder and perform a little better? Anyone have any sound clips of either on their fifth gen? I've searched YouTube and here (to the best of my ability) and haven't come up with any clips. Seems like Mrstacy and mcg_ have the system and like it, but not sure which one they have. Seems like Invidia is a popular choice and that's an option, but if OBX is quieter, I'd rather go that route. Any/all input is appreciated.

[Mrstacy]

^^^ i have the 3" turbo back and it is nowhere close to stock in sound or smell. i could do a video but it is less loud since i got a cat put on one of the resonators. there is a deep growl still, but less so now.

 

i got CELS about cat efficiency without the cat. the obx downpipe is catless. i was advised that putting a cat in the downpipe would make the system less efficient, so i replaced one resonator with a cat. about $200.

 

i got the cat in for the CELs and the awful smell. a mechanic could get rid of the codes as well. ive yet to get smog test, but i think it should pass. i still got CELs with cat. tuner tuned it out.

 

the obx was sold as "no drone" and i think it succeeds. doesn't get under my skin when driving on freeway.

 

overall, i'm happy with the choice

[compsurge]

^^^ i have the 3" turbo back and it is nowhere close to stock in sound or smell. i could do a video but it is less loud since i got a cat put on one of the resonators. there is a deep growl still, but less so now.

 

i got CELS about cat efficiency without the cat. the obx downpipe is catless. i was advised that putting a cat in the downpipe would make the system less efficient, so i replaced one resonator with a cat. about $200.

 

i got the cat in for the CELs and the awful smell. a mechanic could get rid of the codes as well. ive yet to get smog test, but i think it should pass. i still got CELs with cat. tuner tuned it out.

 

the obx was sold as "no drone" and i think it succeeds. doesn't get under my skin when driving on freeway.

 

overall, i'm happy with the choice

 

 

If you have actual emissions test, you won't pass with a $200 cat. You are looking $400 minimum for the converter itself to pass.

 

The tuner didn't "tune it out", they disabled the CEL/MIL code from reporting. You will pass with OBDII plug-in emissions compliance testing since the computer is not reporting any issues.

[mijophil]

^^^ i have the 3" turbo back and it is nowhere close to stock in sound or smell. i could do a video but it is less loud since i got a cat put on one of the resonators. there is a deep growl still, but less so now.

 

i got CELS about cat efficiency without the cat. the obx downpipe is catless. i was advised that putting a cat in the downpipe would make the system less efficient, so i replaced one resonator with a cat. about $200.

 

i got the cat in for the CELs and the awful smell. a mechanic could get rid of the codes as well. ive yet to get smog test, but i think it should pass. i still got CELs with cat. tuner tuned it out.

 

the obx was sold as "no drone" and i think it succeeds. doesn't get under my skin when driving on freeway.

 

overall, i'm happy with the choice

 

Awesome, thanks for the reply. How do you feel the sound compares to others you've heard, as far as loudness goes? I understand I can't get a "quiet" aftermarket exhaust, but I just want the quietest one I can get away with, while still going stage 2. I don't have to worry about inspections in Indiana, so I'd probably leave it as is without the cat and have the CELs tuned out.

[FLlegacy]

I would recommend, going with a catback and then getting a pro tune, either dyno or etune. The aftermarket has yet to present a good solution for making more power than that on the stock turbo. The typical stage 2 isn't going to add much if any power but will get you some torque gains. It is a minor improvement over stage 1, for a lot more money.

[Mrstacy]

If you have actual emissions test, you won't pass with a $200 cat. You are looking $400 minimum for the converter itself to pass.

 

The tuner didn't "tune it out", they disabled the CEL/MIL code from reporting. You will pass with OBDII plug-in emissions compliance testing since the computer is not reporting any issues.

 

Compsurge hits on a key point. There are hidden costs to obx exhaust to stay in compliance.

 

In hindsight, i'd do a 5" nameless Axle back and do an access port tune. But your goals are different than mine. I wanted some growl

[Mrstacy]

Awesome, thanks for the reply. How do you feel the sound compares to others you've heard, as far as loudness goes? I understand I can't get a "quiet" aftermarket exhaust, but I just want the quietest one I can get away with, while still going stage 2. I don't have to worry about inspections in Indiana, so I'd probably leave it as is without the cat and have the CELs tuned out.

 

 

I'd say if stock is zero, this is a 3. Maybe even 4. Nameless 5" I've heard is a 5.

 

I paid about 600 for the tbe 400 to install and 200 for cat. Could have gotten nameless for less than half that and installed myself

[FLlegacy]

Nameless axlebacks are very expensive, $479 with 5"mufflers and then shipping on top of that.

[Mrstacy]

^^^ agree it does cost a bit , but easier to resale if you part out your car. Plus easy self install. Also no tune is required.

[mijophil]

Cool, that's what I was hoping to hear. OBX seems like a quality piece at a very reasonable price. Being it is one of the quieter exhausts at a reasonable price, I'll probably pull the trigger soon.

[FLlegacy]

The nameless axlebacks alone aren't very loud with the 5" muffler, you will hear them when cold from say inside your house but it is more like a mellow low tone. When warm you will have to get on the gas to hear them when driving.

 

As far as a retune, there is always power to be had with the axlebacks and tune.

[Mrstacy]

Cool, that's what I was hoping to hear. OBX seems like a quality piece at a very reasonable price. Being it is one of the quieter exhausts at a reasonable price, I'll probably pull the trigger soon.

 

I was actually agreeing with FLlegacy that the OBX TBE is NOT the way to go but to instead go with an Axleback exhaust. Unless you don't mind a rotten egg like smell and aren't concerned with passing a smog test AND you will install it yourself.

 

Like FLlegacy said, no power is to be derived from the OBX as compared to a simple axleback exhaust.

[mijophil]

I will be installing whatever I get myself, so that's not a concern. My 05 wrx was catless and I don't remember a terrible smell. I will look at axle backs though if the performance gain between catback vs axleback is about the same. Thanks again for the input.

[mcg_]

As far as a retune, there is always power to be had with the axlebacks and tune.

 

I think there was some initial feedback in these forums when the 5th gens were released that there were gains to be had from axlebacks but I believe that consensus has determined that aftermarket axlebacks result in zero power addition.

[mcg_]

Seems like Mrstacy and mcg_ have the system and like it, but not sure which one they have.

 

Sorry man, I haven't installed any of it. Also, I didn't realize there was 2 difference sized systems - in fact, I kinda doubt it. Can you please post a link to the smaller one?

 

FWIW, I'm looking forward to getting rid of my 5" Nameless axlebacks because (1) they don't fit well and (2) the sound is just a little too much for me.

[Humble Rumble]

Sorry man, I haven't installed any of it. Also, I didn't realize there was 2 difference sized systems - in fact, I kinda doubt it. Can you please post a link to the smaller one?

 

FWIW, I'm looking forward to getting rid of my 5" Nameless axlebacks because (1) they don't fit well and (2) the sound is just a little too much for me.

 

What sort of fit issues have you had with your Nameless? I have the same ones and had no issues installing them, and after some fiddling and some anti-seize on the hanger stems, was able to get both cans pretty much dead-centered in my exhaust cutouts.

[Unsp0kn]

$400 to install a bolt on exhaust? Wow.

[FLlegacy]

I think there was some initial feedback in these forums when the 5th gens were released that there were gains to be had from axlebacks but I believe that consensus has determined that aftermarket axlebacks result in zero power addition.

 

Not true. There is about a half psi boost gain just by using axlebacks with the ots tune. The stock cans are restrictive, the confusion comes from losing power from boost cut with a complete tbe vs just axlebacks. The limit is in what the turbo can flow efficiently. A complete TBE will almost certainly get you to overboost, but a free flowing exhaust with stock cans is kind of a sweet spot with the stock turbo. It is all give and take.

 

There is more power to be gained with a better intercooler paired with a downpipe than pairing the downpipe with a complete exhaust, because the turbo is already maxxed out with an aftermarket downpipe.

[mcg_]

Not true. There is about a half psi boost gain just by using axlebacks with the ots tune. The stock cans are restrictive, the confusion comes from losing power from boost cut with a complete tbe vs just axlebacks. The limit is in what the turbo can flow efficiently. A complete TBE will almost certainly get you to overboost, but a free flowing exhaust with stock cans is kind of a sweet spot with the stock turbo. It is all give and take.

 

There is more power to be gained with a better intercooler paired with a downpipe than pairing the downpipe with a complete exhaust, because the turbo is already maxxed out with an aftermarket downpipe.

 

Thank you for the explanation. I have some comments/questions.

 

(1) Wouldn't 1/2 psi result in very little change in CFM, which in turn, would result in very little, or almost zero, gains? Additionally, can you point me to the data that supports this. For example, a stage 1 dyno plot of a LGT without aftermarket cans and a stage 1 dyno plot of the same LGT with aftermarket cans would suffice.

 

(2) I think there are plenty of folks with a full TBE that don't get overboost. For example, I think there are many folks with the Invidia catted TBE that don't have overboost issues.

 

If you are saying that the stock turbo doesn't gain anything by an exhaust that flows better than the stock exhaust + downpipe and that freeing-up the exhaust any more (than stock exhaust + downpipe) is just an unnecessary risk because it may lead to overboost conditions, I completely agree with you.

 

(3) Likely due to the few numbers of these cars in the states (and that it would be timely and costly to do), there really isn't very good data about what aftermarket parts by themselves provide gains. For example, nobody has provided data pre- and post-aftermarket TMIC with the aftermarket TMIC being the only factor changed (besides updated tune to compensate). I suspect that most aftermarket TMICs provide a very little amount of gain and may even negate gains. For example, although it is a different engine, I think the NASIOC threads regarding aftermarket TMICs for the FA20 enlightened a lot of folks about many snake oil TMICs. I think Fredrik940874 has experienced some of those issues.

 

I suspect that the Racer X TMIC and AVO TMIC provide almost zero gains for our cars. I would love for somebody to prove otherwise.

[Mrstacy]

$400 to install a bolt on exhaust? Wow.

 

Invoice says it took 4 hours. He mentioned frozen bolts. Normally a good shop.

[mijophil]

Can you please post a link to the smaller one?

 

http://www.ebay.com/itm/OBX-Cat-Back-Exhaust-Fits-09-10-11-12-13-Subaru-Legacy-GT-2-5L-2-5T-Turbocharged-/162123461453?fits=Year%3A2010%7CModel%3ALegacy%7CSubmodel%3AGT&hash=item25bf4fb34d:g:xJIAAOSwvg9XdvuY&vxp=mtr

 

These look very similar, but looks like they have round mufflers instead of oval, and the description notes a 2" OD instead of 3" like the other.

 

What do you all think about this? I wonder what kind of upgrade it would be over stock. After reading about downpipe and tune, maybe that's the route I need to go since I'm not really looking for an increase in sound, just power.

[Ellesedil]

I thought the magic recipe for going stage 2 with stock sound levels was to upgrade the downpipe and keep the CBE stock. Considering that, you could probably get just about any Legacy aftermarket downpipe along with the Grimspeed exhaust adapter and be fine.

[FLlegacy]

Thank you for the explanation. I have some comments/questions.

 

(1) Wouldn't 1/2 psi result in very little change in CFM, which in turn, would result in very little, or almost zero, gains? Additionally, can you point me to the data that supports this. For example, a stage 1 dyno plot of a LGT without aftermarket cans and a stage 1 dyno plot of the same LGT with aftermarket cans would suffice.

 

(2) I think there are plenty of folks with a full TBE that don't get overboost. For example, I think there are many folks with the Invidia catted TBE that don't have overboost issues.

 

If you are saying that the stock turbo doesn't gain anything by an exhaust that flows better than the stock exhaust + downpipe and that freeing-up the exhaust any more (than stock exhaust + downpipe) is just an unnecessary risk because it may lead to overboost conditions, I completely agree with you.

 

(3) Likely due to the few numbers of these cars in the states (and that it would be timely and costly to do), there really isn't very good data about what aftermarket parts by themselves provide gains. For example, nobody has provided data pre- and post-aftermarket TMIC with the aftermarket TMIC being the only factor changed (besides updated tune to compensate). I suspect that most aftermarket TMICs provide a very little amount of gain and may even negate gains. For example, although it is a different engine, I think the NASIOC threads regarding aftermarket TMICs for the FA20 enlightened a lot of folks about many snake oil TMICs. I think Fredrik940874 has experienced some of those issues.

 

I suspect that the Racer X TMIC and AVO TMIC provide almost zero gains for our cars. I would love for somebody to prove otherwise.

 

1. My personal experience was maxxing out around 16.96 psi regularly on a cobb ots stage 1 tune. Installing nameless 5" axlebacks got me to 17.49 psi with no other change. So without a single other change I gained a 1/2 psi boost, which means the turbo was better flowing with the axlebacks...rocket science I know sorry I didn't realize the significance at the time or I would have logged both runs in VD for you. With tuning I would have no doubt been able to pull 18-19 psi without an issue. Which is a pretty significant gain IMO.

 

2. I think you are mistaken, there are not that many 5th gens running a full TBE with no overboost ever. Make a poll and see for yourself.

 

I am saying an aftermarket downpipe with an otherwise stock exhaust coupled with an aftermarket intercooler (FMIC would be best) would allow a more consistent power increase over an aftermarket TBE on its own. The heat produced by our turbo in the high rpm range is the limiting factor for making power. Hence the many flamethrower comments by tuners.

 

And remember just because a part doesn't make more power doesn't mean it isn't doing anything. If an intercooler can keep your power more consistent no matter the temps outside its working. Not all gains are measured in HP/TQ.

[Rutchard]

2. I think you are mistaken, there are not that many 5th gens running a full TBE with no overboost ever. Make a poll and see for yourself.

I'm not going to say I never overboosted with the Invidia catted TBE, but it came up pretty rarely for me. Only happened if I mashed the throttle in 6th at low RPM.

 

I think the folks with overboost issues are louder than the ones without.

[FLlegacy]

I'm not going to say I never overboosted with the Invidia catted TBE, but it came up pretty rarely for me. Only happened if I mashed the throttle in 6th at low RPM.

 

I think the folks with overboost issues are louder than the ones without.

 

Agreed, but it seems to be pretty common in certain low temp conditions with a full TBE, which I would be curious to see who is actually running a full TBE vs parts of one or restricted ones.