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#1
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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?
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#2
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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.
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#3
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Exhaust mods
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) |
#4
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certain amount of back pressure
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 |
#5
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#6
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I agree...I think
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.
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Time for my very own long list of mods: 92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler I don't care if Subaru says it's STI...it will always be STi to me |
#7
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Re: Exhaust mods
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#8
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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.
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Matt Locker Link 2015 BRZ Limited 6MT 92 Ebony LS-L ECUtune Stage2av1, Z32 MAF, 370cc injectors, TomsSVX intake, BontragerWorks 22mm RSB #003, HID Hi and Lo beams, OT endlink and bushing mods, PWR Aluminum radiator, Harvey's QC shift kit, 2.5" flowmaster 80 exhaust, 17" Michelin Pilot Sport A/S, Poly sway bar bushings, Slotted Bradi rotors, AFBeefcake powdercoated calipers, 97 grill, and a huge set of air horns. 300,000 miles and counting 92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles 19 Subaru Ascent Premium - -Hers !. 89 DL 4x4 little red wagon - a.k.a. The immortal suby. 275k R.I.P. |
#9
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for simplicity purposes.
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.
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1994 SVX, true dual Magnaflow exhaust, K&N filter, 17" Enkei RS6 wheels, Bridgestone Potenza RE730 225/45/17 rubber, zinc plated cross-drilled rotors with yellow painted brake calipers. B&M tranny cooler rated at 19,000 GVW. GC springs and Koni strut inserts installed and the car is lowered two inches all the way around!! "Too much fun to drive!" |
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