Exhaust and BackPressure

I am intersted in doing the exhaust on my svx, while the car was at my mechanic I looked underneath and it seems as though there is alot of restriction on the stock pipes..lets say I didn't have to worry about passing emissions. Would my car function better if the two cats were gutted, as well as what ever is in the other two cat looking things after the two pipes come together. i know that non turbo engines need a certain amount of back pressure, if this were to be done along with the exhaust upgrade from motorsports would that be to much?
Thanks

[svx_commuter]

Well I do not know the answer but there are a fair amount of posts on this subject. The exhaust does limit the horsepower if you want to modifiy the stock engine, turbo, NOX, larger injectors but for the stock engine and injectors there isn't much gain from what I have read. You could search on the subject in the data base. Lots of history there.

I'm no tree hugger, but I would'nt suggest gutting the cats. A better solution (performance and preservation wise) would be hi-flow monolithic cats. I personally am going through Random Technology out of Georgia(?). I would highly suggest them.

As for performance, if you do a free-flow cat back and then hi-flow cats you might as well go the final yard and extrude hone the exhaust manifold and replace the complete intake tract. Two caveats with this route though:

1) you may need a fuel computer since the stock intake/exhaust tracts virtually *suffocate* the H-6. The ECU may freak if the engine is suddenly free to inhale fully.
2) the stock Subaru MAF sensor (and MAFs in general) tend to be on the fragile side. A free-flow intake will probably kill the stock sensor.

BTW- there are 3 cats on the SVX (the third is the "y" junction)

Donovan,

This is not coming from me but from a friend who builds dirt race cars.

He said you would still need to have, at the very least either the CAT or the Muffler. If you didn't have any when you hit the gas you would have no zoom / power.

And that would be for each side. So 1 CAT or 1 muffler. You can't run wihtout them.

Not my opion, My buddies.

I havn't got a clue but he was looking over my shoulder here at work when I read this and that's what he said.

Wayne

[cocacola08]

Originally posted by svx_commuter
Well I do not know the answer but there are a fair amount of posts on this subject. The exhaust does limit the horsepower if you want to modifiy the stock engine, turbo, NOX, larger injectors but for the stock engine and injectors there isn't much gain from what I have read. You could search on the subject in the data base. Lots of history there.

Putting Kinetic Concepts cat-back system, plus "gutting" the main cat, gained nearly 1/2second in the 1/4 mile..with no other mods

[SVX10]

I would go along with Cocacola08 and say that the KC does some good. I have their intake and exhaust along with the UR lightweight underdrive pulley. In a recent 0-60 judging by the counter on my CD player, it was under 8 seconds, I would almost venture to say closer to 7. I know the stock SVX claims 0-60 anywhere from 6.9 to 7.6, but either way I think there is some improvement. The only thing with KC is that you gotta wait a long time...I waited nearly 8 weeks for mine. OK...now I'm rambling. What I wanted to ask is...Hey, Cocacola08, where'd you get your cat gutted (gross ) and how much did it cost...mine is rattling like crazy so I think it may be something I want to do. I have heat shields off, so I know it's not those that rattle. Did you gut it or have a y-pipe put in...I was thinking about that. Right now I'm low on funds due to paying for a new retainer and a 13 over speeding ticket, but in a few weeks I'll be getting my pay check, then I can take care of that and the 97 grill. Anyway...lemme know some of the details. Thanks
Mat-1

Just to make this post somewhat on topic, I think a good setup is the 2 primary cats and a free flow exhaust.

Originally posted by SVXtypeR
I'm no tree hugger, but I would'nt suggest gutting the cats. A better solution (performance and preservation wise) would be hi-flow monolithic cats. I personally am going through Random Technology out of Georgia(?). I would highly suggest them.

On a side note, If you're looking for a Random Tech Cat, check out www.rollhard.com The guy in charge is Eloy. Tell him you heard about the site from Chris from the 240sx list and he may cut you a break . . . then again, he may get irritated and charge you extra. When I left that list (due to totalling my 240sx) he was in the middle of a "discussion" and appeared ready to leave the list. No one could play nice over there.

[immortal_suby]

I have been experimenting with my exhaust for a while now and at one time had complete open pipes - no cat or muffler. I did not notice any decrease in power but it was louder than any harley I've ever heard. With straight pipes and a dynomax super turbo it was still too loud. With pipes and a flowmaster - too loud. I now have pipes, a glasspack and a flowmaster. It is fairly quiet, it feels faster in the top end.

[1994SubaruSVX]

you may want to go with a setup similiar to the one described at motorsportwarehouse.com, he basically replaces the oversized muffler on the stock svx with a magnaflow and eliminates the resonator. i would also suggest getting at least one high flowcat. i left the stock cats at the motor. i did not want to replace the maf......i still may have to because my car idles weird sometimes.