Got a question and looked all over, whats the stock diameter of our exhaust? I need to buy another cat to pass smog and not sure what size inlet to get. Its stock with 80's series catback SPecs on the left <-------------------

Being a TBI car, it's probably 2 1/4, but I'm not sure. A well opptioned car could have the larger 2 3/4. But I havent seen but a few the the larger pipe.

thanks, should i get a 2.50 then so it can slip over the stock pipe, or should it be welded without being slipped on?

Lol I got 2 3/4 for my v6. Thats what the guy at napa gave me so i guess its right..

Id go with the 3.0 but i dont wana mess with step ups or downs, just gotta get me by till i get back in indiana and dont have to worry about smog

Post #4 of the following link may be helpful:

http://www.thirdgen.org/techboard/ex...-question.html (85 Z28 Exhaust Question)

JamesC

Thanks James!
If i get a 2.50 that should leave enough clearance to slip the cat onto the tubes and weld? I wana make it easy for my family member who will be welding it, I had a buddy do my last one and he wasn't very good at the welding, ended up having to go buy sleeves and use them to weld the cat in.
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2" outlet manifolds with single 2 1/4" y-pipe
82-87 305 LG4 (VIN H)
88-92 305 L03 (VIN E)
82-83 305 Crossfire
90-92 305 LB9 w/o G92 axle (VIN F)

2 1/4" outlet manifolds with single 3" y-pipe
83-86 305 L69 (VIN G)
85-89 305 LB9 (VIN F)
88 350 L98 (VIN 8)
89 350 L98 w/o G92 axle (VIN 8)

2 1/4" outlet manifolds with dual 2 1/4" cats
89 350 L98 w/G92 axle (VIN 8)
90-92 350 L98 (VIN 8)
89 305 LB9 w/G92 Axle (VIN F)
90-92 305 LB9 w/G92 (Vin F)


Above information was posted by TransamGTA350

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TBI and V6 engines should have come with a 2 1/4" cat from the factory. Putting a 2 1/2" cat on it will be a good upgrade.