I was wondering what you advise: I have a 87IROC L98 with stock exhaust manifold. I have 2 questions: 1. What size is the stock manifolds? I need to know, the car has a flowmaster 3inch catback, but I need to know what the input would be for the cat.

2. What kind of cat would you reccomend?

 

Via www.TPIS.com

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200-402 Catalytic Converter, Corvette/Camaro, L98, 1986-1991, 3in Slip-in, 2-bolt flange........$220.00

 

Buy a direct fit Catco cat for your model year.

 

I guess summit or Jegs would know what the input pipe is for it?

$220 sounds a little high for the expected gain. I could just install it to pass emmissions and then put the pipe back in. That has to be better than a $220 cat.

 

You can by 3" in and 3" out cats and then just use muffler clamps to hold it on if u wanted. I have one of those laying around that I still need to install, waiting for my headers though.
.

 

Thanks, but what if the stock manifold output is smaller than 3' ? Will that be a problem?

 

I would think a hollowed out cat would certainly be cheaper.

 

My 87 IROC had a stock 3" exhaust system, so a 3" in & out should work. I said in a previous post buy a Direct fit Catco cat for your car and be emission legal. About $118 from Summit.

 

Thanks guys.