What is the stock sizes on a cat from a 89 RS? I've been thinking of a 3" cat back. Will it just bolt on, or will have have to modify something? I'm guessing the stock size is 2 1/2" right? Thanks

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89 RS Camaro, 305 TBI
Mostly Stock
Duel Snorkel Air intake

- Future Mods -
DynoMax Street Headers
DynoMax Cat Back

 

The stock cat outlet is 2.25" If you buy the right cat-back for your car, even if it is a 3" I pipe, it will have a cone reducer to mate up to your cat.
BUT, if you are planning on running headers/ or any hope on mkaing your car fast, then you should hold off until you can afford headers or a bigger y pipe for a 3" cat. Otherwise you'll have to modify the front of the cat back to mate up to the 3" cat later.
...ed

 

I am looking at getting headers at the same time as a cat-back. I do eventually plan on more mods to the car later. So from what everyone else seems to be doing, perhaps I should look into a new cat also. or for a temp fix modify the cat with fittings to accept a 3" pipe, until I can afford the cat. would this be a good idea also?. Since I have no idea how much cats are.. So a 3" system (headers & all) would probably be better in the long run then. Thanks.

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89 RS Camaro, 305 TBI
Mostly Stock
Duel Snorkel Air intake

- Future Mods -
DynoMax Street Headers
DynoMax Cat Back