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downpipe alternative, need your opinion

hpa-gtii

Ready to race!
What do you think about taking the oem downpipe and cleaning out the first catalytic converter? That way only the second CAT will be in use and the whole setup will look oem because nothing is changed on the outside. I could also get APR Stage 2 software to take care of any CELs. Your opinion please.
 

Axleman

Ready to race!
1) Hollowed out cats sound like crap. A big hollow can attached directly to the turbo outlet would probably sound really bad.

2) I bet it wouldn't flow much better either. 3" Turbo outlet to 5-6" hollow can to squished 90 degree turn doesn't sound like it would work very well.

3) When you go to stage 2, most of the gains you get are from the downpipe replacement, very little comes from the software upgrade. I don't see any benefit with what you propose. Sorry.
 

hpa-gtii

Ready to race!
What about removing the first CAT and replacing it with a pipe? Thanks for responding.

1) Hollowed out cats sound like crap. A big hollow can attached directly to the turbo outlet would probably sound really bad.

2) I bet it wouldn't flow much better either. 3" Turbo outlet to 5-6" hollow can to squished 90 degree turn doesn't sound like it would work very well.

3) When you go to stage 2, most of the gains you get are from the downpipe replacement, very little comes from the software upgrade. I don't see any benefit with what you propose. Sorry.
 

Axleman

Ready to race!
What about removing the first CAT and replacing it with a pipe? Thanks for responding.

Have you seen the factory downpipe and how the precat is made into it? It doesn't look like it would be very practical or easy to try remove it from the factory pipe. I suppose you could have a shop fabricate the upper portion of the downpipe and weld it to the rear section where the second cat is. But the whole point of replacing the downpipe is for increased flow and this approach only goes halfway really.

What exactly are you trying to accomplish?
 
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plac

Guest
people have tried to clean them out. huge pain, and if you leave any particles in there they can get broken loose and sucked in on decel. overall just not a good plan any way you look at it. better off buying a $150 ebay pipe and testing it out if youre gonna do that. no advantage to "look stock" with your oem downpipe when you can't pass emissions anyway.
 

hpa-gtii

Ready to race!
I want a dp that not restrictive like to oem and I want the quietness of the oem pipe diameter. I want the AWE pipe but I don't like their 1 year warranty.

I suppose you could have a shop fabricate the upper portion of the downpipe and weld it to the rear section where the second cat is. But the whole point of replacing the downpipe is for increased flow and this approach only goes halfway really.

Wouldn't it run like the AWE dp?
 
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plac

Guest
I want a dp that not restrictive like to oem and I want the quietness of the oem pipe diameter. I want the AWE pipe but I don't like their 1 year warranty.

Very good points. The pipe size doesnt have as much relation to noise as the cats and resonators do. There are a few other options for a catted/resonated downpipe aside from AWE which is the highest priced. (42dd, Ultimate Racing come to mind.)
 

Axleman

Ready to race!
I want a dp that not restrictive like to oem and I want the quietness of the oem pipe diameter. I want the AWE pipe but I don't like their 1 year warranty.



Wouldn't it run like the AWE dp?

Probably not since the exhaust must still go through a very dense factory cat. The AWE pipe has a high flow cat. FWIW, any mod you would do on the factory pipe would kill the warranty on it, so I'm not sure why AWE's 1 year warranty would bother you.

I think plac is right though. Get one that is catted and resonated to keep things quiet.
 

hpa-gtii

Ready to race!
So Plac, you're saying that pipe diameter does not affect sound only cat and res?

Very good points. The pipe size doesnt have as much relation to noise as the cats and resonators do. There are a few other options for a catted/resonated downpipe aside from AWE which is the highest priced. (42dd, Ultimate Racing come to mind.)
 

hpa-gtii

Ready to race!
I don't like AWE's 1 year warranty.

Probably not since the exhaust must still go through a very dense factory cat. The AWE pipe has a high flow cat. FWIW, any mod you would do on the factory pipe would kill the warranty on it, so I'm not sure why AWE's 1 year warranty would bother you.

I think plac is right though. Get one that is catted and resonated to keep things quiet.
 
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