any know if there is much power gains from removing cat pipe and replacing it with a test pipe ! i have a rough idea that it wont be noticeable but yeah better flow/lighter is what i think. anyone from experience felt gains!
vtecintegra,
Dec 10, 4:26am
I guess it depends on the car. I removed the 15 year old cat on my older Integra and noticed no difference at all
lazz323,
Dec 10, 4:27am
yeah i got a integra type-r running a/m headers (maxim work 4-2-1) + standard itr system 2 1/4"
cuda.340,
Dec 10, 2:46pm
pulled the cat off a supercharged corolla levin, made zero difference to performance, the exhaust note became annoying so i fitted a bullet muffler to change the note a tad.
sw20,
Dec 10, 2:47pm
Some cars are noticeable, some aren't.
My old Clio 172 developed a leak around the cat join so I just had it cut out and replaced with straight pipe. Only made the car a bit noisier.
My mr2 turbo on the other hand picks up several WHP, mainly due to the nasty 90 degree bends the gases have to go through in and out of the stock cat converter, which has been replaced by a 3" downpipe.
marte,
Dec 10, 7:38pm
Used converters are worth money,
mellisa2000,
Dec 10, 7:49pm
Around $60 or so, maybe $90 for big ones.
kazbanz,
Dec 10, 7:52pm
lazz--JUST ripping out the cat isn't going to make any difference at all.-Assuming the cat isn't totally blocked up and severely blocking the air flow. However I'd be interested to see what would happen if the cat was removed and a freer flowing air filter was fitted AND the ecu was reset back to factory so it had to relearn the air flow in and out. I'd wonder if it gave increased perfoirmance,increased fuel economy, just reset the fuel mix back so the fuel/air was normal or did nothing at all
vtecintegra,
Dec 10, 7:57pm
Probably nothing on an ITR - the factory intake is pretty hard to improve on.
Also that exhaust may or may not be an improvement over the standard one.
lazz323,
Dec 10, 9:51pm
thanks for the reply. yeah i was thinking that prob wont make much difference unless the full 2.5" system was added to the equation :) will probably look for a system first because i might find one that has cat deleted already . never know but if i do find a catback will def be looking for a test pipe :D
lazz323,
Dec 10, 9:56pm
anyone know anywhere in wellington they do custom exhaust! want to make a 2.5" mandrel bent exhaust :)
wrong2,
Dec 12, 3:53am
except that its way too long with too much restriction & has a rediculous double runner set-up
as for the OP - just removing the cat & doing nothing else wont make much difference
a full extractor system however can make up to a 30% jump in power when the intake has been also freed up to allow the vacume to do its work
male_timaru,
Dec 12, 10:44pm
From my chats with both mechanics and Exhaust specialists (on my E30 BMW) some vehicles benefit more from the back pressure than others and the removal of the Cat is only going to improve economy and power in vehicles that do NOT require as much back pressure, etcTurbos for instance do (in most cases) result better with cat removal, whereas N/A non-back pressure reliant vehicles don't
That was the gist of what 2-3 different people have told me .
pollymay,
Dec 12, 10:48pm
NO NO NO NO, backpressure is WRONG. I hate hearing that word, backpressure is ALWAYS bad. It's exhaust velocity that makes the difference, no car benefits from backpressure cept maybe some 2 strokes
vtecintegra,
Dec 12, 11:47pm
I don't think any of that is correct - 30% power increase especially
Go jump on nzhondas.com and see what power various people are making with various setups.
sr2,
Dec 13, 1:27am
So that's where I've been going wrong after all these years!
wrong2,
Dec 13, 2:04am
low torque engines - as in low RPM small trail bikes - go better when there is some restriction in the system as opposed to a complete free flow pipe
wrong2,
Dec 13, 2:07am
1999 RF 900
american model converted to NZ spec
116 Hp stock - 150 Hp after the exhaust change/airbox junking
motorbikes generally have higher a higher state of tune & get a bigger HP increase from an extractor change than cars do
vtecintegra,
Dec 13, 6:35pm
We're talking about an (almost certainly) Japanese spec ITR. Which IIRC doesn't have the dual intake runners that the standard B18c does.
I don't see how motorcylces are relevant to a discussion about cars.
marte,
Jun 10, 1:58pm
If yah wanna original exhaust note, make the rear muffler out of copper.
Had a XR250 with a copper rear muffler, unmistakeable sound, real head turner. Brass'd do a similar thing too.
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