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i have a helix downpipe with the stock catback system. a mechanic was telling me that the exhaust system was creating to much backpressure and i was losing performance with the downpipe. is this true or not?
 

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No, in general opening up the pipes and removing cats will remove backpressure, increasing performance. tell him to give you a technical explanation.
 

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twrx007 said:
i have a helix downpipe with the stock catback system. a mechanic was telling me that the exhaust system was creating to much backpressure and i was losing performance with the downpipe. is this true or not?
I don't know specifics about the helix dp, but I would figure that the smaller design of the muffler isn't helping.
 

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um... no... you got rid of the 2 d/p cats which will greatly have reduced the backpressure in your car... the stock catback is still fairly restrictive but you really wont see much benefit in replacing it until your moving more air (ie bigger turbo).

So basically either the mechanic lied, or was retarded.
 

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MustGoFast said:
um... no... you got rid of the 2 d/p cats which will greatly have reduced the backpressure in your car... the stock catback is still fairly restrictive but you really wont see much benefit in replacing it until your moving more air (ie bigger turbo).

So basically either the mechanic lied, or was retarded.
I couldn't disagree more. You do not need to replace your turbo to move more air. Just cut out the restrictions, like the 3 cats (uppipe especially) and you will have more power. Add a boost controller and engine management and you will wipe the floor a stock wrx. The wrx has huge upgrade potential w/o upgrading turbos.
 

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thats the best part of the car...the exhaust has such modding potential..uppipe is always the best place to start in my opinion!
 

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twrx007 said:
i have a helix downpipe with the stock catback system. a mechanic was telling me that the exhaust system was creating to much backpressure and i was losing performance with the downpipe. is this true or not?
my next mod is removal of the dp (bosal) and attachment of a STi muffler (and I may use the STi mid pipe which shipped with my muffler... mostly cuz it's spankin new). that should be enough back pressure release for a while...and keeps a cat in for sniffer purposes.

my up cat has been gone since December 03... since it's pre-turbo I don't think it has much backpressure impact but I know losing the catted dp will help.

my 2 cents....

-tp
 

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I may be wrong, but I belive to little backpressure will give you less torqe. Of course everyone "knows" you have to loose all you cats, but 2,5" exhaust may be much than a 3" or 3,5" untill you get a big turbo and stuff..

(Having that said I also wan to say that I'll getting a 3" myself just in case ;) and becuase I hopfully will get a giant turbo some day;) )

I'm also under the impression that correct backpressure is more important on NA cars.

Hp sells cars, tourqe win races :tongue:
 

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mind you it's 7am, but in a turbo car you don't want back pressure. on a n/a setup, you do to maintain torque.

if I have that backwards, I can easily blame it on the time of day!
 

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Roffa said:
I may be wrong, but I belive to little backpressure will give you less torqe. Of course everyone "knows" you have to loose all you cats, but 2,5" exhaust may be much than a 3" or 3,5" untill you get a big turbo and stuff..

Hp sells cars, tourqe win races :tongue:
You are an NA guy, aren't you? A loss of backpressure can = major power loss for a NA engine, because you need to maintain that balance.

In a turbo car, the less backpressure you have, the faster and more freely your turbo can spin. You can take it from there.
 

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Blue2004WRX said:
You are an NA guy, aren't you? A loss of backpressure can = major power loss for a NA engine, because you need to maintain that balance.

In a turbo car, the less backpressure you have, the faster and more freely your turbo can spin. You can take it from there.
Nope.. But my first car (BMW) was NA, the rest have been turbo...
Well I said I could be wrong :) But anyway I doubt you'll see much diffrence between a 2,5" and a 3" exhaust, unless you go big..
 

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Roffa said:
Nope.. But my first car (BMW) was NA, the rest have been turbo...
Well I said I could be wrong :) But anyway I doubt you'll see much diffrence between a 2,5" and a 3" exhaust, unless you go big..

My first car was a BMW too. W00t! You're right, until you upgrade a lot, you wont need much bigger than 2.5. its easier to just do it right from the beginning though, just in case.
 

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Re: Re: question about backpressure

Teep said:
my next mod is removal of the dp (bosal) and attachment of a STi muffler (and I may use the STi mid pipe which shipped with my muffler... mostly cuz it's spankin new). that should be enough back pressure release for a while...and keeps a cat in for sniffer purposes.
..

-tp

FYI- The STi cat back is the EXACT same inner diameter as the WRX one.... It just has a cooler looking tip.
 
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