Have a 89 305 TBI looking for a good catback system that goes to dual 2 1/2"- 3" after
the muffler, any suggestions?

 

I have been very happy with the Hooker Aerochamber system I run, its 3" all the way (your's would be 2.5" at cat to 3"). In all acctuality, between Flowmaster, Dynomax, Edelbrock, and Hooker, its just what sound and style you like best, they all flow about equally.

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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 with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Catco 3" High-Flow Catalytic Converter, Hooker 3" Aerochamber Cat-Back System, Transgo Shift Kit, Performance Resource Chip, Accel Ignition, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET: 14.32 @ 97.7mph
(corrected for elevation)