noob exhaust questions?

Exhaust 101...

 

How would various exhaust mods rate considering concerns:

1. Bang for the buck (power increase, cool sounds, etc)

2. Ease of installation (shady tree, or do I need a lift?)

3. Livability (noise, both outside to others, like cops, and inside to ME)

4. Emissions legal

5. Warrantee

6. Effects on other parts and systems, ECU, whatever

 

Not knowing a lot, I guess the various mods, or combinations thereof, would include cat-back (or cans and/or midpipes only?), down pipe, up pipe, headers...

 

To me, cat-backs seem pretty easy to put in, maybe down pipe also. Both at same time? Headers seem like more of a hassle?

 

I have 05 LGT wagon MT, daily driver, so must stay legal... Up to 27k miles now, so I might wait a while if warantee issues. Not to mention $$$$.

 

If something like this is discussed in another thread, let me know. I looked around and did not find much that was this general. Thanks...

Do what I did. Get yourself a gutted stock d/p and catback exhaust (any muffler shop can throw some 3" piping and magnaflows on for cheap). That will give you a great sound and boost in performance. Don't do headers, not worth it if you just want basic power/noise, especially without a custom tune.

 

What you really want is an Accessport, StgI is the most bang for your buck. Then when you get an up-pipe to go with your downpipe you can flash StgII. Then you'll ask yourself "why didn't the car come from the factory like this?"

Is all that stuff emissions legal? Shouldn't I use a catted dp to stay legal? What about Subie warrantee?

Know anything about XO2 racing cb? $430 incl shipping on ebay, found it on another thread. Seems like an awesome deal.

Is it a waste to keep the stock dp? There is an Autospeed catted dp for $350, would that be enough of an improvement to justify cost?

Might consider the accessport a bit later...

A downpipe is a downpipe. I'm sure there are some that will yield minor gains over others but no piece of metal is worth $100+ more than the other. I picked up a gutted stocker for 60 bucks. Somebody back me up on this but I'd hazard to guess you get 90% the benefit of a larger diameter, after market pipe. I picked up the stocker so I would look stock, meaning the dealer would have to take the pipe out and look in it to see there's no cat.

 

I passed emissions with 2 of the 3 cats missing in my WRX.

 

You would be amazed at how much the AP improves the power and responsiveness of the car. I would definitely recommend getting it first. Use the money you save by getting a gutted stock d/p .

since a downpipe is post turbo it doesnt do that much of a gain, after the turbo its usually whats the best way to reduce backpressure....

since a downpipe is post turbo it doesnt do that much of a gain, after the turbo its usually whats the best way to reduce backpressure....

I don't think that is true. I got gains when I added a Crucial shorty DP(3") and PDE up and a stage 2 tdc map. If you reduce back pressure you turbo will spool faster. I drove like that for a few days and did a custom 3" SS mandrel bent setup for the shorty back. I added a 3" hi flow cat, 3" Borla XR1 as a resanator and a y to dual 2.25" magnaflows. It's not too loud and no droning on the highway. The car pulls like a monster now. But all this won't really do much without an AP. I would say save you money for a AP. It has alot o pros like in stop and go traffic to downtown LA I'm getting about 23.5mpg.

So what AP? Cobb seems the best, or can I get something more basic for less $$$ ($650 ouch)?

Also, what do you think would have a bigger effect, a decent catted down pipe (like the Autospeed that I can get for $350) or a good cat back (GReddy, Autospeed or the xo2 racing one that I can get on ebay for $430 incl shipping?)

Again, want to keep it basically smog legal...

Also, while on the subject, I would assume the stock ECU map is to pass emissions regs? And remapping for better performance means it probably wouldn't pass? And what happens to engine longevity with a performance reflash? I plan on keeping this car a long time, want to stay fairly worry free. I drive faster than most folks, but I don't really thrash it, don't launch it....

So what AP? Cobb seems the best, or can I get something more basic for less $$$ ($650 ouch)?

Also, what do you think would have a bigger effect, a decent catted down pipe (like the Autospeed that I can get for $350) or a good cat back (GReddy, Autospeed or the xo2 racing one that I can get on ebay for $430 incl shipping?)

Again, want to keep it basically smog legal...

Also, while on the subject, I would assume the stock ECU map is to pass emissions regs? And remapping for better performance means it probably wouldn't pass? And what happens to engine longevity with a performance reflash? I plan on keeping this car a long time, want to stay fairly worry free. I drive faster than most folks, but I don't really thrash it, don't launch it....

 

You can get a used Cobb v.1 for about $400.

Check. Get the AP first, reflash to stage 1. Downpipe (catted for smog) and up pipe, possibly also a CB, then reflash for stage 2.

I think I might wait on this... up to 27 k, warantee out at 36k. Also need the $$$ right now. Doing suspension mods first anyway, getting JDM rsb and JDM spec b struts and springs, I suppose that will have to be enough to amuse myself for a while.

In the meantime, thanks for the advice. Cobb DP seems very well regarded, might get that. How about Up Pipes? Rigid vs. Flex?

Also looks like learning ins and outs of cel's might require a college course.

I recently added the AP to my LGT 5EAT and the results are amazing. No more jumpy acceleration. The turbo spools so much sooner which creates smoother acceleration and faster get up. Right now i'm running stage 1 maps, but I want to be able to run stage 2 maps. My car is totally stock. What do i need to do to be able to run stage 2? I know i need a high flow catalytic converter to run this map. Is this achieved by getting a new downpipe, up-pipe, or both? Thanks for your time:lol: oh yeah, i got my AP v.1 for 400 on ebay. Works like a charm. no complaints.

FWIW I just had an up-pipe installed about a week ago. From experience I can tell you 80-90% of the gains my butt dyno feels came from just the down pipe. The up-pipe added marginally quicker spool and a wee bit more power. I just wanted it in there to know that the cat wouldn't break up in the up pipe and become turbo food.

Check. Get the AP first, reflash to stage 1. Downpipe (catted for smog) and up pipe, possibly also a CB, then reflash for stage 2.

I think I might wait on this... up to 27 k, warantee out at 36k. Also need the $$$ right now. Doing suspension mods first anyway, getting JDM rsb and JDM spec b struts and springs, I suppose that will have to be enough to amuse myself for a while.

In the meantime, thanks for the advice. Cobb DP seems very well regarded, might get that. How about Up Pipes? Rigid vs. Flex?

Also looks like learning ins and outs of cel's might require a college course.

 

Something you have to keep in mind is that altering either the UP or DP (or both) are both illegal. Altering/removing ANY catalytic converters that are functioning (unless proven) cannot be legally altered.

 

That being said. Im going Stg2 with gutted DP & gutted UP. Trying to keep the car looking as stock as possible, and stealthy.

I recently added the AP to my LGT 5EAT and the results are amazing. No more jumpy acceleration. The turbo spools so much sooner which creates smoother acceleration and faster get up. Right now i'm running stage 1 maps, but I want to be able to run stage 2 maps. My car is totally stock. What do i need to do to be able to run stage 2? I know i need a high flow catalytic converter to run this map. Is this achieved by getting a new downpipe, up-pipe, or both? Thanks for your time:lol: oh yeah, i got my AP v.1 for 400 on ebay. Works like a charm. no complaints.

 

The "official" Stg2 is both UP & DP (with either an intake or HF filter I believe).

I believe Cobb's definition of stgII is a full turboback exhaust. Of course a d/p and u/p are almost a full turbo back anyway...

I believe Cobb's definition of stgII is a full turboback exhaust. Of course a d/p and u/p are almost a full turbo back anyway...

 

Yup, sorry. I just omit that fact because I dont really look at CBE's for performance anyways (we get good enough with just UP & DP).

Yup, sorry. I just omit that fact because I dont really look at CBE's for performance anyways (we get good enough with just UP & DP).

 

From what I read stage 2 is just removing the DP cat. Most people remove the first cat because the don't trust it t stay together as the increase power. Removing the up cat also helps improve spool time for better response. I drove around for two days at stage 2 with just my up and Crucial shorty dp and it was a bump from stage 1. But the bump was Bigger once I added the 3" hi flow cat ahd 3" exhaust. If you look up megan racing exhaust GB on this site you will see that Paul( boostjunkie) shows a dyno chart of the exhaust. It was with no tunning and ran the same car with the stock exhaust and with the MR cat back and it made like 11+ tq and I think 7hp over stock. With tunning it should make more.

The DP cat staying together? Thats the reason ppl remove the UP cat, because theyre worried that it will break up and get sucked into the turbine. The DP cat breaking up would merely clog your DP a little bit, cause no real harm to anything (minus extra backpressure until you diagnose the issue).

 

Yeah, CBE's do make power, dont get me wrong. I just dont have that kind of money to spend for 7hp. (Me = poor until summer)

Okay, so I'm reeeaally glad this thread showed up. I, too, am an exhaust noob. If I understand everything I've been reading around this forum (pleeeaase correct me if I'm wrong), an AP is an AccessPort that allow you to hook into the car's computer to "reflash" what I'm guessing are the air-fuel mixtures, etc. to maximize performance at a given stage of hardware. If you have stock exhaust there is a Stage 1 setting on the AP? Then, after replacing the stock UP (up pipe) and DP (down-pipe) you may reflash with your AP to jump to stage II? Catback means from the catalytic converter(s) to the back of the car (mufflers). So, it sounds like the UP and DP are more important initially (with the correct tuning) and the catback stuff is secondary, but can fortunately be done for relatively cheap. If I understand the exhaust correctly, from the cylinders back it goes: header, UP, DP, cats?, midpipe, y, mufflers. I'm sure this needs to be elaborated upon. I'm about to make the stage II jump and am selling my "99 ZX7R for the cash to do it. So as soon as that sells, I'll have plenty of car fun cash . Now, I need the knowledge to do this correctly so that smog isn't an issue and everything is done safely. Please help! Attached is a picture of a $1100 catback exhaust system from the dealer. Seems nice...ripoff? Also attached is my baby. Must sacrifice for suby . If by some off chance ne1 is near Boise, Idaho, I'm selling it for $4500 with tons of matching gear/accessories.

Well, you got it everything right for the most part. But if you go stage 2 you will not be "smog legal". You can't remove any cat and be legal. You can still pass the sniff test but not the inspection. The AP will stop any CEL. You can pick up an AP V.1 for $450 or less. You get no extra power from the AP v.2 just "better" interface. You can use a '05+ STI, '06+ WRX or '07 LGT UP to keep the stock look or get aftermarket UP for around $100. You can get a shorty DP and keep your 3rd cat or get a catt full DP for $350. You can go stage 2 for about $900. Depending on how loud you want your car. You can get a cat back from about $350 (ebay XO racing search site for reviews) to $1100+. Hope that helps.

The AP will stop any CEL.

 

Thanks for the response! What is CEL?

Check Engine Light

The AP will stop any CEL.

 

Thanks for the response! What is CEL?

Check Engine Light.

oic! thanks

Well, you got it everything right for the most part. But if you go stage 2 you will not be "smog legal". You can't remove any cat and be legal. You can still pass the sniff test but not the inspection. The AP will stop any CEL. You can pick up an AP V.1 for $450 or less. You get no extra power from the AP v.2 just "better" interface. You can use a '05+ STI, '06+ WRX or '07 LGT UP to keep the stock look or get aftermarket UP for around $100. You can get a shorty DP and keep your 3rd cat or get a catt full DP for $350. You can go stage 2 for about $900. Depending on how loud you want your car. You can get a cat back from about $350 (ebay XO racing search site for reviews) to $1100+. Hope that helps.

 

When you say you can go to Stage II for about $900 is it UP, DP and AP?. I drive a 06 SWP LGT Ltd Wagon and went Stage II today. Based on what I was reading here on the forum I decided to get the following installed: Cobb UP & DP, Cusco F&R sways with endlinks and oh yes the Cobb AP v.2. ECU was flashed to stage II in the included maps with the unit. I assume this was the base map for stage II. I haven't had a chance yet to read through the manual. I just let the autotek do it. MAN, THE CAR IS TOTALLY DIFFERENT NOW! I have the 5EAT and it pulls nicely. When I through it into sport mode it's just even more amazing. Not bad for a daily driver and grocery getter!

 

One thing also. Is it common for the peculiar smell to be noticed since some of the cats now from the stock UP/DP's are no longer there? When I drove the car home I really noticed it so I decided to pop the hood and also noticed a very light smoke/steamlike emission emit from the engine bay. Is this normal. Is it burning off some oil or something. I drove it again later and it was less noticeable (smell and visual)... it might of been I was inhaling too much of the fumes now!

most likely shipping oils burning off. that should go away. also, now that you've run the car you should get back in there and retorque everything. better safe than sorry for exhaust leaks!