How easy is it to change the cat on a 91 RS V8? Does it bolt right in and out, or is there welding involved? I tried looking but it's hard to tell.

 

The cat bolts to the intermediate pipe with 2 bolts on a flange on the end of the pipe and cat. The other end slips onto the y-pipe. You will probably have to cut the AIR tube and either weld it back yourself or drive to a muffler shop and have them weld it for you.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!