Why is it so hard to find a 3inch catback for an 85 TPI? Which one would be best based on performance/sound (loud!), I plan to add headers and cold air. Thanks

 

It shouldn't be too hard at all, there are a million systems out there. Hooker, Flowmaster, Edlebrock, Dynomax, Borla, Random Technology, Pacesetter, Magnaflow and Flowtech all make cat-back systems for 3rd generation Camaros and Firebirds. I have installed 3 Hooker Aerochamber cat-backs, all came with 3" mandrel bent piping and an Aerochamber muffler. I have installed the systems on my '87 IROC L98, my friend's '85 Z28 LG4, and another friend's '82 Berlinetta LG4. Check at www.jegs.com and at www.summitracing.com to check out which of these systems you would like for your car!

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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)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

it shouldn't be that hard to find. i dunno whats BEST but car sound or catco are pretty good. i have catco on mine with 3' exhaust (flowmaster). sounds good and performs well.

 

The reason I say this is because every catback system I look at says 86-91 but always skips my year 85. Flowmaster for example says 2.5 in /out for 83-85 and 3in/2.5 out for 86-91 and the hooker catback seems to be for 86 and up as well, what is the big difference between 85 and 86? If I get an 86 exhaust will it fit?