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gutted oem down-pipe vs. aftermarket cat-less downpipe


turbotool

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I gutted the first cat only...no stink at all. Gutting the 2nd will probably net you a few extra ponies but not a ton more.

 

Also not sure if this is cat related or not but my buddy decatted both cats on his 06 STI and he gets a pretty nasty backfire on quick shifts and when letting off the throttle at high RPM.. Also, he complains about the stink but I never sensed it at all when driving his car...some people are more senstitive to it than others I guess.

 

id agree stkink issues from in the car are probably a lot to do with sensitivity. Ive ridden 2 strokes all my life so I love all sorts of fumes/smells of engines and dont think id be very sensitive to it...

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Help me interpret that topic/dyno. Is it saying that there isn't much hp/tq left on the table on everything else stock when you compare gutted stock dp and aftermarket catless dp?

 

 

Yep, thats how I read it. Keep in mind that different cars dynoing on different days will not give you a perfect comparison but it will get you a ballpark.

 

According to the one post of the thread I linked:

 

"So on P&L's DynoJet I put down 242WHP and 291WTQ

A stock STi on the same Dyno puts down 247WHP and 268WTQ

A STG2 MT LGT With an up-pipe and down pipe, filter and Perrin Topmount did 254WHP and 295WTQ"

 

He was running a basic Stage 2 tune with a gutted DP (I am not sure if it is both cats or just the first) and I believe he still had a cat in his up pipe.

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I gutted the first cat only...no stink at all. Gutting the 2nd will probably net you a few extra ponies but not a ton more.

 

Also not sure if this is cat related or not but my buddy decatted both cats on his 06 STI and he gets a pretty nasty backfire on quick shifts and when letting off the throttle at high RPM.. Also, he complains about the stink but I never sensed it at all when driving his car...some people are more senstitive to it than others I guess.

never had any back fire in mine. I'll be going stg 2 later this year on the STI.... I've had a few people complain about stink, but never noticed it myself (used to it i guess?)

Wiggle wiggle wiggle wiggle wiggle yeah!!!
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I have a stock midpipe sitting in my garage...I might just gut it and install it this summer.

an extra one? if so... do it. seriously, 15 mins.

Wiggle wiggle wiggle wiggle wiggle yeah!!!
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So a catback involves ... what parts specifically? Y-pipe and cans?

 

This got me confused initially too...someone please correct me if I am wrong..especially about the resonator.

 

On the stock exhaust (post turbo) there are 5 parts:

 

1 - Downpipe - Shorty section (with cat) bolts to

2 - Downpipe - Mid pipe section (with cat) bolts to

3 - Exhaust - Midpipe (with resonator) and

4 - Exhaust - Y pipe bolts to

5 - Exhaust Mufflers

 

When you hear "Catback Exhaust" that means Pieces 3 through 5.

 

When you hear aftermarket downpipe it usually means pieces 1 and 2...some aftermarket DP manufacturers offer a "shorty" DP, that would only be piece 1.

 

I would always confuse 2 and 3 since they are usually referred to by the same name (midpipe).

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