Turbo back exhaust
 

All the DB Tuned talk got me thinking. Along with some brake work for next year, a turbo back exhaust would not be a bad idea. Question to you all is the best make and models (cats vs no cats etc.). Figure I should get a custom tune after its all done. Anyway, thanks for any ideas on my winter projects. Additionally, I'm also looking into Hoosiers but need to get a rule book first and figure out what size will fit the wagon's front wheel wells.

To attain the maximum power and the fastest spool and while spending the least money you could go catless.

You'll also save money if you get a "long" DP that replaces the stock DP and the 3rd cat (mid pipe). Then any normal aftermarket CBE just bolts up to the Long DP.

I like Divorced Waste Gate DP's myself since people who tune have told me they make it easier to tune boost since the WG gases aren't slamming into the rest of the exhaust at the largest point of turbulence, the leading opening of the DP.

However, most say there's really no large difference in performance between a good bellmouth DP and a DWG. Cobb makes their canned maps on a bellmouth, so some people who use the canned maps decide to go with with a bellmoouth for that reason, but Cobb doesn't say it's necessary.

I'd also suggest that you either buy a ceramic coated DP (and UP if you don't have one) to keep the exhaust gasses hot and therefore, quickly moving and to keep engine bay temps low. A good aftermarket turbo heat shield (or modding your stock one like most people do to allow for the larger DP) will be smart too. If you go with non-ceramic coated DP and UP's, you can heat wrap them, but it's kind of ghetto since it can unravel and fall apart and even rust your pipes all the way through eventually even if you use heat wrap sealent spray.

Catless is stinky and louder. I run a Crucial DP and UP. Both pipes are top notch and come with a high quality ceramic coating inside and out. The DP is DWG and a "shorty" DP so I'm still using the stock 3rd cat. Ed says that when/if I go to a catless midpipe (race pipe), I can expect ~8-10whp and I believe I'd see faster spool to some small degree. Replacing the OEM midpipe with a high-flow cat midpipe would be expensive but would still give me ~5whp I think and would hopefully keep the stinkyness and noise down.

I also run the Borla Hush CBE which is amazingly quiet for a straight through true 3" design, but I don't think it looks all that amazing and it's not cheap. Honestly, for a stage 2 WRX, 3" isn't necessary for the CBE. I could be running a straight through 2.5" CBE and I doubt it would effect performance.

Hope that helps. :)

Here's a cool diagrahm in case you haven't seen it.

Coated DP is unnecesary, though it is a good idea onteh up.

I am a firm believer in divorced wastegate pipe. The longer the better. My BP merges after the bend at the bottom.

I would encourage you to keep at least one cat. High flow is fine. It will make any future smog requirements they might add most likely passable, and it does help the environment.

On the exhaust, I would suggest having a removable "silencer" so if you get a fix-it ticket for noise, or just want a quiet drive somewhere, you can slap it in.

And yes, I would get a tune after a turbo back...

The only reason I suggest to coat or wrap the DP is to keep the heat inside and away from the IC. The stocker has heat shielding for this reason.

A modified or replacement heat shield is probably better than any coating.

The heat chimneys are also an interesting options.

As I understand it, even with the turbo heat shield modified and installed, plenty of DP heat will find it's way to the IC and the rest of the engine bay when the car isn't moving.

The Invidia products are well built and reasonably priced. I suggest the N1 race with headers if you want a good laugh!

If anyone could get away with that setup, it would be the D-man!

Hahah, Damn it sounds weird though.

Thanks for the ideas guys. Anybody have an opinion on Hoosier race tires on the wagon? I would like to know if one set would last a full autoX season.

No, I don't think they will last a whole season.

The street tire modifier effects my class time but how about PAX guessing the same or no?

If it's just you driving on them and you can get some decent camber they should last. They won't be as fast in October as they were in May but they should be usable.
I would look at the Kumho V710s as well. They are as fast and should last longer.

The .968 modifier affects both class and pax times.

Is there something in the rule book about wast gates? No, I can't look it up Dean and the print on-line is to small. I'll get a rule book soon.

Grab the PDF, and do a search.

Wastegate changes of any form = Street Mod