Retrofitted CAT removed stock up-pipe vs. Aftermarket cat-less up-pipe: results

Master Of Pain · Sep 30, 2002

Ok guys, without 1,000 witnesses and approval from the Finnish Scientific Consortium, the results from the track and 4-wheel dyno are in.

Conditions:

78F
55% humidity
Sea Level

Vehicle baseline
Base 2002 Subaru WRX Sedan Manual +
Turbo XS MBC
Stock Airbox +K&N -Resonator

Stock uppipe -cat or
"Leading Brand" aftermarket uppipe (name ommited to defray abuse)

Pull avg w/stock up-pipe -cat

223 HP 234TQ

1/4 Mile 3 Run avg:
60' ... 1.916
1/8 ... 8.721
MPH ... 84.24
1/4 ... 13.409
MPH ... 102.14

Pull avg w/aftermarket

223 HP 233TQ

1/4 Mile 3 Run avg:
60' ... 1.941
1/8 ... 8.692
MPH ... 84.16
1/4 ... 13.423
MPH ... 101.98

Stocker done on Sat, Aftermarket on Sunday. Had alot of fun with the changeout. Just thought you guys would like to see what a minimalistic mod approach can do for you - and the payoff of de-catting the stocker uppipe.

Both up-pipes acted the same. Period. Same top end, same low end grunt, etc. I could not percieve a diffrence.

Master Of Pain · Sep 30, 2002

And to those who want to raise the BS flag or want to dispute the hundreds of diffrent factors that could have tainted the end results:

GO EAT A BAG OF TOENAIL CLIPPINGS

I have my bloody scarred hands to prove it.

Have a nice day.

QuickSilver · Sep 30, 2002

Thanks.
I found your post to be very helpful. Good techinical overview of the comparison. I always wondered what type of gains came from the gutted OEM pipe. The choice of up-pipes is a big one for most people (me included)...now w/ up-pipes included with after-market headers, the choices keep growing.

Verdugo · Sep 30, 2002

Nice post! Although the bag of toenail clippings didn't sit well with my stomach this morning...

JTREX · Sep 30, 2002

Just curious, what did you do with the material you removed from the stock uppie?

JohnZim63 · Oct 1, 2002

Nice research, especially since it was paid for in blood and knuckle skin. Certainly no surprise in the results. But what happens when you need to put it back to stock? Some of us have an aversion to non-reversible mods. I figured that my peace-of-mind is worth the price difference between an aftermarket pipe and a new oem pipe.

nyxjf · Feb 20, 2003

thnx for the infos.

How much did you pay for your gutted uppipe?
also, people in i-club claims that uncatted stock uppipe will have strange air flow, due to the original catted design. I guess they're wrong?

WRX · Feb 20, 2003

MMMMMmmm toenail clippings!! *crunch crunch*

capt'n'caveman · Feb 20, 2003

so what bout an aftermarket up-pipe, not the gutted stocker? can you get some data on that too, since you've already est. a baseline

QuickSilver · Feb 20, 2003

I'm not sure what your question is, but this thread compares the performance of a de-catted stock up-pipe and an after-market uppipe (which brand was not disclosed).

ANyways, thanks for bumping this thread up (I forgot all about it)...I know there's another up-pipe thread with the same topic.

Hg.

capt'n'caveman · Feb 20, 2003

ohhhh, ok.....i read it wrong.....when you wrote "Stock uppipe -cat
" i took that as, your stock up-pipe, WITH the cat....but i guess you meant, the stock up-pipe MINUS the cat.....

nevermind bout my earlier question then.....good results...since i got the stock gutted up-pipe, hehe

plac · Jan 17, 2008

capt'n'caveman said:
ohhhh, ok.....i read it wrong.....when you wrote "Stock uppipe -cat
" i took that as, your stock up-pipe, WITH the cat....but i guess you meant, the stock up-pipe MINUS the cat.....

ya i saw it that way too... now it makes more sense..

Porkgrisle · Feb 20, 2003

Just curious what was you boost set at?

lambosv21 · Feb 20, 2003

so one more torque for the decatted stock eh?

Big Sky WRX · Feb 21, 2003

Good job! I can appreciate the bloody knuckles and I only had to do it once.
I for one am not suprsied, not only are you getting the same gains- it looks stock, has heat shields, won't leak and the price is tough to beat!

Someone needs to figure out how to gut the downpipe and maybe rework the wastegate flange on the stocker.

Again good job.

Big Sky

brembo · Feb 21, 2003

Temps/humidity/barometric pressure similar on the two days? Not disputing, just curious.

Also, the hp and torque numbers...those at the wheel? Or crank estimated? Seem high for wheel with the list of mods ya have up there. Again just curiosity, I'm liking the idea of guttin the cat more and more.

Rich10 · Feb 21, 2003

Great post. I don't think that I had read this before. It seems to drive home the point that the gain is from removing the cat.

I would be interested to see a comparison test of downpipes. Is a bellmouth better than a split design for the wastegate or is the stock design (without the cat like the HKS downpipe) perfectly acceptable with the stock turbo.

Big Sky WRX · Feb 21, 2003

Rich10 said:
Great post. I don't think that I had read this before. It seems to drive home the point that the gain is from removing the cat.

I would be interested to see a comparison test of downpipes. Is a bellmouth better than a split design for the wastegate or is the stock design (without the cat like the HKS downpipe) perfectly acceptable with the stock turbo.

I think the oe (HKS) design has been shown to be less than optimum vs the bellmouth and divorced design. Between those two, I've heard lots of different (opposing) opinions. Ofcourse removing the cat provides the most gain in the downpipe also, so differences may be neglible.

Big Sky

ebr0t · Feb 24, 2003

HMMM.... VERY interesting, now gotta find a link to how to gut the uppipe

Master Of Pain · Feb 24, 2003

brembo said:
Temps/humidity/barometric pressure similar on the two days? Not disputing, just curious.

Also, the hp and torque numbers...those at the wheel? Or crank estimated? Seem high for wheel with the list of mods ya have up there. Again just curiosity, I'm liking the idea of guttin the cat more and more.

Read the first post again.

capt'n'caveman · Feb 24, 2003

ebr0t said:
HMMM.... VERY interesting, now gotta find a link to how to gut the uppipe

http://webpages.charter.net/baraboo_halls/auto/wrx/up/uppipe_fix.html

brembo · Feb 25, 2003

Master Of Pain said:
Read the first post again.

Ahhh, I missed that bit, sorry to be a pest. So which one are you going to keep? Aftermarket or OEM gutted? I'd be tempted to go with OEM to keep leaking problems at bay, and look stock.

Sea Dragon Rex · Feb 25, 2003

Did you happen to get any numbers with the stock uppipe and intact cat?

Master Of Pain · Feb 25, 2003

I didn't get the dyno on the stock unit as I gutted it prior to testing. The only other thing I am going to test is a bellmouth catless downpipe (bolt-in) vs. stock. That should leave in one cat to pass emissions with and plenty of flow.

RLsChMiDt · Mar 11, 2003

Wow! One of the more useful threads EVER!

jugger · Mar 11, 2003

WHO CARES????

thanks for posting results for the rest of us to see...wish there were more ppl like you....but someone help me out here....why the hell should someone buy a new up-pipe or gut theirs...the results SUCK perdy much nothing changed...i think i could do better things with $200 than buy a piece of metal pipe to put on my car..... it just doesnt make sense...

Verdugo · Mar 11, 2003

Re: WHO CARES????

jugger said:
thanks for posting results for the rest of us to see...wish there were more ppl like you....but someone help me out here....why the hell should someone buy a new up-pipe or gut theirs...the results SUCK perdy much nothing changed...i think i could do better things with $200 than buy a piece of metal pipe to put on my car..... it just doesnt make sense...

Are you kidding me? No cats in the uppipe allows your turbo to spool up faster, not to mention you don't run the risk of your cat breaking up and destroying your turbo as well as lowering your EGTs...those reasons alone are enough to invest in a catless uppipe or gut your stock one.

Retrofitted CAT removed stock up-pipe vs. Aftermarket cat-less up-pipe: results

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