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Discussion Starter #1
So, I had a plan on what I was going to do to my 1988 Vette this winter but since we are getting our first cold front in New York, I'm opting to just stockpile all the parts I need and just wait until spring to install them. I guess you can say I don't do the cold very well.

I was about to place my first order with a vendor here but one question arised, will I show a code if I run a striaght pipe instead of a catalytic converter? Besides power gains, what are the other pros, and cons?

There are emissions laws in NY, but I'm not concerned with that.
 

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DC Crew
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You won't show a code, so long as everything else is in running order.

But there's no reason to run a straight pipe these days, high flow cat converters flow near as well while keeping your Vette legal and creating cleaner fumes. It's win-win.

http://www.digitalcorvettes.com/forums/showthread.php?t=58303

Not to mention, high flow cats will cancel a lot of the annoying in-cabin resonance you would get from a straight pipe.
 

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you won't throw a code unless you remove or disconnect the oxygen sensor. our C4s don't have after converter 02 sensors like most OBDII vehicles. You'll also have to do something about the air pipe running to the converter-- unless you've already removed the smog pump and related gear.

no real benefit to removing the converter if it's not clogged and high flow. You may actually induce a little more of the resonance in the exhaust and it could be a little stinkier than with the converter.
 

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Discussion Starter #4
First off, thanks for the replies guys.

Right now my car is stock with the exception of the exhaust system which I plan on replacing anyways. I was thinking since I want the headers and a new cat-back exhaust system, it would be easier to do the cat too and all at the same time. I was thinking Melrose headers and Corsa cat back, but I was debating on high-flow cat or test pipe. If I go with the test pipe, I could probably have the guy weld a connecter for the smog hose. Do you guys know of a direct fit (bolt on) high flow cat for my car?
 

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First off, thanks for the replies guys.

Right now my car is stock with the exception of the exhaust system which I plan on replacing anyways. I was thinking since I want the headers and a new cat-back exhaust system, it would be easier to do the cat too and all at the same time. I was thinking Melrose headers and Corsa cat back, but I was debating on high-flow cat or test pipe. If I go with the test pipe, I could probably have the guy weld a connecter for the smog hose. Do you guys know of a direct fit (bolt on) high flow cat for my car?
This could be your chance to be rid of the smog pump and put a pulley. You don't have to run air to the CAT. I never did. Originally, I gutted the cat and sealed up the air pipe so I never needed it. Put on a Random Tech cat because I wanted to cut out some of the resonance. RT Cat has a tube for AIR but I deleted it a long time ago so I never had it installed. Pulley there only. If it wasn't for the resonance, I'd have gone without the cat.

Sure it stinks a little but WGAS? I drive forward for the most part not backwards so I don't breathe it.
 

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First off, thanks for the replies guys.

Right now my car is stock with the exception of the exhaust system which I plan on replacing anyways. I was thinking since I want the headers and a new cat-back exhaust system, it would be easier to do the cat too and all at the same time. I was thinking Melrose headers and Corsa cat back, but I was debating on high-flow cat or test pipe. If I go with the test pipe, I could probably have the guy weld a connecter for the smog hose. Do you guys know of a direct fit (bolt on) high flow cat for my car?

I know everyone here is sold on very expensive TPIS type systems and headers-- But until someone show real world dyno tests i'm not a believer. What I can tell you is that running the stock headers into a 3 inch pipe through a high flow cat into 3 inch rear y pipe and through dynomax muffler will yeild you 2-3 PSI back presure behind the cat at idle and one hell of a great sound-- for about $1500 less than a really expensive system.

You can buy a copper pipe cap at HD and block off the smog pump air check valves and either have the EGR crossover nipples welded closed or seal it off with some weld stick putty and screw the same size cap onto it-- no it's not a true threaded surface but with the weld putty and cap it will seal and hold.
 

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I know everyone here is sold on very expensive TPIS type systems and headers-- But until someone show real world dyno tests i'm not a believer. What I can tell you is that running the stock headers into a 3 inch pipe through a high flow cat into 3 inch rear y pipe and through dynomax muffler will yeild you 2-3 PSI back presure behind the cat at idle and one hell of a great sound-- for about $1500 less than a really expensive system.

You can buy a copper pipe cap at HD and block off the smog pump air check valves and either have the EGR crossover nipples welded closed or seal it off with some weld stick putty and screw the same size cap onto it-- no it's not a true threaded surface but with the weld putty and cap it will seal and hold.
Just throwing in my 2 cents here....
You don't need an expensive name brand anything. I went to a local muffler shop that had a very qualified welder and master pipe bender. They cut out the Y-pipes and the single cat, and replaced starting at the stock exhaust manifolds, new 2-3/4" pipes into dual hi-flo cats back to my existing mufflers. The key item also added, was an X-pipe.

She sounds great and I can feel a significant increase in performance. I had my car on a dyno before, so I have a benchmark... I need to dyno her again to see exactly how much of an improvement my $500 got me. :D

Oh, and I had the air pipe (going to the cat) capped off. The welder guy cut and then pinched the end closed and welded it shut. No codes!!
 

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Discussion Starter #8
Thank you all for your input, I appreciate it.

I ordered my Corsa cat back system amongst other toys for the vette. After the holidays I'll order my headers and y-pipe. I have to spread it out or the wife will flip out. I won't order the high flow cat until spring time, when the weather gets warm. So, I have a few months to figure what I'm going to do. So far, I'm leaning towards the test pipe, but I have a few months to figure it out.

Thanks again guys.
 

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:buhbye: I put the Freeflow pipes without CATS and mine runs great! Just remember that the New Pipes may be alittle larger and the stock mufflers may not quite fit
 

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I just installed a Corvette Central straight pipe w/Magnaflow Mufflers on my '93. I got the car in 2006 and it has ran 9.30 to 9.35 on our local 1/8 mile track since the day I got it. Now it runs 8.9 to 9.0. That is a quantifiable result I can attribute to the exhaust since I haven't done anything else to the car.

Jim
 

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I just installed a Corvette Central straight pipe w/Magnaflow Mufflers on my '93. I got the car in 2006 and it has ran 9.30 to 9.35 on our local 1/8 mile track since the day I got it. Now it runs 8.9 to 9.0. That is a quantifiable result I can attribute to the exhaust since I haven't done anything else to the car.

Jim
And magnaflow mufflers sound awesome. I had them on an 84 and they were by far my favorite mod.
 
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