Greetings everyone –

Does anyone know who (if anyone) makes a 3” downpipe / front center section combo that bolts up to any US spec cat-back exhaust system WITH a cat NOT in the downpipe section. (i.e., not right after the turbo).

For example, the MRT downpipe is a 3” w/cat that would work, but the cat is inline right after the turbo outlet. Same thing for the AVO pipe, Stromung pipe, AND Perrin downpipes.

The theory is that you would get less turbulence/better performance moving the cat further away from the turbo, like the TurboXS, Vishnu, or BPM cat’ed exhaust systems.

Or would the exhaust flow characteristics not be changed enough to matter?

If all else fails, anyone want to buy a used Greddy EVO cat-back?

Thanks in advance!

 

A Perrin downpipe would be your best bet. It will fit very nicely with the Greddy although the cat is in the downpipe (near the turbo).

Dan

 

I like the TurboXS setup the best. You don't have a downpipe cat, plus it tapers from 4" to 3" utilizing the theory of the ventrully effect (exhaust gas contracts as it cools) for better flow. You have the third cat in the traditional location and can replace it with a off road straight through pipe to run catless sometimes. You shouldn't have any problems mounting a standard mount muffler to this setup either.

 

I haven't seen the Flatt racing pipe, but here's the response on the BPM unit - no dice with the Greddy EVO (or any other factory matching cat-back)

>> The BPM downpipe will not fit up to your stock center pipe (it >> is 3" in diameter whereas stock is 2.5"). If the Greddy is 3" in >> diameter, it will likely match up however. The BPM twin-dump >> downpipe is catless only- I'm not sure if they make a catted >> downpipe, but we don't stock it if they do.
>> Brian - Subaruwrxparts.com

As far as the TXS model, it is awesome, except it will only match up to an AXLE-Back muffler. I thought about having my Greddy exhaust cut to match up with it, but the cost seems a bit much.

TXS exhaust + custom work on Greddy - chance of shop screw up = not a good option.

So far the general response I've got is that the cat right after the turbo isn't a big issue. Not ideal, but for <400hp not an issue.

Any more thoughts?

 

One other thought - TurboXS would make a killin' if they sold (in addition to their existing mid-pipe) a shorter mid-pipe to match up with any other stock cat-back setup. Then they could sell exhausts to fit any setup... Even at the same price or a little less, I'm sure they'd sell quite a few.

hint-hint TXS!

 

Just to wrap up this thread, I've been convinced that the turbulence/back pressure generated by having a cat in the downpipe section isn't that big of a HP difference, and have decided on the Perrin DP with cat.

Thanks for everyone's help!

J.

 

have you looked at the BPM turbo back exhaust, the cat on this system is where the third stock cat is. I have heard nothing but rave reviews on the BPM twister III, hope this helps

 

I emailed BPM, unfortunately it won't match up to an aftermarket cat back. They use 3" piping all the way back, where the stock tapers to 2.5".

I'm going to sell the Greddy cat-back and buy a whole new exhaust. Anyone interested PM me - it's only 3 months old.