I have an 87 IROC with Single CAT and 350 TPI/700R4. How do i know if i have the 3 inch or 2.5 inch cat? There are two flomaster amercian thunder systems that fit this car. 17233 and 17234. One is for 3 inch, and one is for 2.5 inch cat's. They both have 3 inch exits. ------------------ 87 Iroc Z 350 TPI, Automatic (700R4) 32,000 Original Miles!! Have not driven in 3 years. No work yet I once whipped a c5 vette!!

Well, my 88 had 3", but that doesn't necessarily mean anything. You could measure the outside circumfrence of the pipe and convert it to find the diameter. A string works well if you don't have one of those tape measures that you often see tailors using. If my calculations are correct, the circumfrence should be close to 9.42". Hope that helps.

Matt

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irocet@hotmail.com

drive.to/Stang_Kilr

88 IROC-Z -- 350 L-98, 700R4, Flowmaster, Edelbrock Headers, Catco Cat, K&N, MAF Sceens Removed, Airfoil, March Pullies, Comp Cams Magnum 1.6 Roller Rockers, Bosch Platinum Plugs, Accel 8.8 mm Wires, MSD 6AL, Hypertech Cap & Coil, Hypertech Chip, Hotchkis Strut Tower Brace

I recently bought the #17233, they both use the same intermediate pipe size of 3 inches, but the 2.5 of the 17234 is tailpipe size if I'm not mistaken. 17233 is for '5.0L AND 5.7L HIGH OUTPUT ENGINES' and the 17234 is for '5.0 AND 5.7L LOW OUTPUT ENGINES' if I remember right...

How does it sound?? I am also looking at the Hooker Cat Backs. More importantly, is there much of a power increase??

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87 Iroc Z
350 TPI, Automatic (700R4)
32,000 Original Miles!!
Have not driven in 3 years.
No work yet
I once whipped a c5 vette!!

Sorry, dont' have it on yet. I need to replace the fuel gauge sending unit which is in the gas tank, and to do that I'd have to rip off the exhaust so I didn't install the Flowmaster yet. I think you can get something like a 10% increase and a possible increase in gas mileage. I've heard quite a few Flowmasters and they sound great, but eveyone has them now so they don't sound different and unique. You could look into the Hooker, I was going to get it originally but I got a discount so I went with the Flowmaster instead and it came out to about the same price.

What is the model of the Hooker Cat Back, and how much is the system compaired to the 320 dollar flomaster's??

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87 Iroc Z
350 TPI, Automatic (700R4)
32,000 Original Miles!!
Have not driven in 3 years.
No work yet
I once whipped a c5 vette!!

I'm not positive but I think it was 16823, but don't quote me on that. I think it's something like $259. I've heard it along with a header install(there is a soundclip on this board somewhere) and it sounded kickazz.