What cat would go best with the Hooker Cat-back system? It will be going my 86, 305 TPI, nothing but stock IROC. They are upgradeable right?

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86' IROC-Z
5.0L TPI
Stock(for now)

 

One thought: if the exit of the cat is larger than the O.D. of your intermediate pipe, you will have to neckdown from the cat to the intermediate. The resulting backpressure will create turbulence and reduce output. The power loss will be more pronounced at higher rpm's, leading you to feel like low rpm torque has increased. Go with a 3" cat to match the 3" intermediate pipe(which will be plenty for the stock y-pipe). If you are still using the stock y-pipe, you will need to buy/fab an adapter to mate it with the 3" cat.

Ooops, guess that was more than one thought!

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He who hesitates,... is lost!

 

So, if I don't replace the cat and keep the stock one, does that mean my aftermarket exhaust from Hooker won't work??

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86' IROC-Z
5.0L TPI
Stock(for now)

 

itll work but it really wont be complete...it will have not been used to its full potential. i mean whats the point of a free flowing exhaust if your cat is choking up your whole system. later

 

Ok, makes sense. But what about what 88IROCs said? About some adapter or something??

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86' IROC-Z
5.0L TPI
Stock(for now)

 

thats what hes saying...if you have a 2.25" cat like some camaros come with and your cat back is 3 inch **** is gonna be messedup. also works vice versa...if you have a 3 inch hi flow cat and get a 2.5 inch cat back...which is just dumb...you will have to use a reducer. just pick out some headers...i like hookers...but the ones i want arent smog legal, buy my cat, and get a nice cat back. Good luck man. let me know if you have any more q's

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Rick
90 Camaro RS 305 TBI
400 small block, Hooker 1 3/4 super comp long tubes, Random Tech Cat, Hooker aero chamber cat back on the way!!
TH700-R4 with Trans-Go shift kit
MacEwen Motorsports White Gauge Overlays
K&N Filter Charger (wooohooo)
GTS Headlight and Taillight covers
5% Limo Tint all around
Classic White Chevy Bowtie sticker on rear window
www.geocities.com/esvalenz

Man if my camaro were a rice-rocket all those mods would give me what...easily 50-60 hp!!!

 

Go with a cat that matches it's exit diameter with the diameter of the intermediate pipe. There are cats available from companies like Dynomax that have different sized inlets and outlets. That way you can match your 2.5" y-pipe to your 3" intermediate pipe. Go that route if you don't think you'll be getting headers. However, if at some future point you plan to upgrade to headers, buy your new cat with that in mind. In this case, your best bet would be to buy a cat with 3" inlet/outlets and have a muffler shop make an adapter to mate your 2.5" y-pipe to the cats 3" inlet. Getting this adapter made will take the muffler shops 10 - 15 minutes max. Then you won't need to buy a new cat when you get headers.

One other thing: try to find a cat with flanges welded on at both ends. This may mean you have have to weld flanges onto the y-pipe and/or the intermediate pipe(again, something any competent muffler shop can do in a short amount of time). However, it is my experience that a flange and gasket seals better and seals longer than slip-on connections.

Ooops, one more thing,... Talk to some people in your area and find out who the really good muffler shop in your area is. Then talk to the muffler guys about your current plans, and your future plans, and find out what their recommendations are.

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He who hesitates,... is lost!

[This message has been edited by 88IROCs (edited November 22, 2000).]