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*HELP* - GPX piping size

Posted: Mon Dec 15, 2003 5:05 pm
by lal
can someone please tell me what the stock piping size from extractors to cat... cat to muffler is for a GPX? 2.25" or 2.5"??

I've got a quote to put a 2.5" piping from cat back with a cannon muffler (XFORCE) for $600... is that cheap compared to what you (others) may have spent??

Posted: Mon Dec 15, 2003 7:02 pm
by smorison
Imho there is no point in doing an exhaust system without putting in a highflow CAT - when they comply them they use cheap ones that tend to be restrictive.

CAT back (inc cat) anything around 1000.00 is a good price.

Posted: Mon Dec 15, 2003 9:38 pm
by hnm738
so what is the stock pipe size?

cause now im just thinking that i done have a real exhaust but just a different tip


i got my muffler change the other day and the guy said i got a 2.5" from front to back with a massive resonator ???? i done feel any power different compared to another car?

Re: *HELP* - GPX piping size

Posted: Tue Dec 16, 2003 7:39 pm
by D-TRAIN
lal wrote:can someone please tell me what the stock piping size from extractors to cat... cat to muffler is for a GPX? 2.25" or 2.5"??

I've got a quote to put a 2.5" piping from cat back with a cannon muffler (XFORCE) for $600... is that cheap compared to what you (others) may have spent??
Stock is 2.25"

2.5" is about as much as you want to go for a NA FTO.

$600 is a good price for a cat-back. Haven't heard anything good or bad about XFORCE.

As a guide, a good Japanese cat-back exhaust is around the $1000 mark.

Posted: Tue Dec 16, 2003 8:09 pm
by D-TRAIN
hnm738 wrote:so what is the stock pipe size?

cause now im just thinking that i done have a real exhaust but just a different tip


i got my muffler change the other day and the guy said i got a 2.5" from front to back with a massive resonator ???? i done feel any power different compared to another car?
Power gains are going to be minimal with little or no other mods.

You'd notice the exhaust tone more than anything else.

Posted: Wed Dec 17, 2003 12:29 am
by hnm738
just wandering if i take out the resonator what would the gains be and how louder would it be....

sat in a friends wrx and it feels smoother when gaining speed and can feel the g force

for about $1500 what can i do to gain extra? will i be looking at 10-15kw extra at the wheels?

Posted: Wed Dec 17, 2003 12:45 am
by hnm738
was just wanderin much kw at the wheel does a stock tip gpx have?

Posted: Wed Dec 17, 2003 1:36 am
by GPXXX
hnm738 wrote:just wandering if i take out the resonator what would the gains be and how louder would it be....

sat in a friends wrx and it feels smoother when gaining speed and can feel the g force

for about $1500 what can i do to gain extra? will i be looking at 10-15kw extra at the wheels?
removing the resonator will undoubtedly increase noise emissions from the exhaust, so unless you like to have yellow stickers on your windscreens I suggest u keep 'em, because the amount of gains simply does not worth the risk and extra noise (which can get annoying at times). in fact other than the noise, you won't feel any difference in terms of performance on the road...

as for the WRX, bear in mind that the car is turbo'd and if he runs higher than normal boost, there is a crapload more gas that needs to be passed through the exhaust so by removing the resonator you are releasing some backpressure which allows the gas to flow freely (which also results in increased performance and noise). and the G-force you feel is when the turbo kicks in, typical with all other turbocharged cars...

however i still don't believe it makes a world of difference like you have described - it's all in your mind IMO. I have been taken for rides in other turbocharged cars with/without resonators and frankly they don't feel that much different...

Just my 2c...

Posted: Wed Dec 17, 2003 7:05 pm
by smorison
the resonators on a FTO are not restrictive (well no more than a straight-through exhaust) its not worth taking htem off unless you want 0.5-1kW gain, with this sort of gain if you can feel it its all in your head.