Ive noticed a great deal of popping and sometimes even backfiring coming out of my exhaust these last few weeks. at first i thought it was totally normal, but its been getting annoying. i heard that my exhaust donuts could be bad, i took my car to midas and they couldnt find anything, what do i do now? are there any exhaust valves that need to be replaced? any ideas? thanks- ------------------ 1987 LG4 Camaro z28 Performance KN airfilter, flowmaster 80 series and catco high flow cat, 180* thermostat System Panasonic CQ-DF200U deck, fosgate speakers (hpc1369, frc2246)

Most likely there is an exhaust leak somewhere.

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'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
FLOWMASTER, NO CAT
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat
3:73 Posi
Rebuilt 700R4 vette servo and .500 boost valve
B&M Megashifter, 5" Autometer Tach w/shift lite
Soon to be installed
3" Hooker Aero Chamber

i had them check for an exhaust leak and they couldnt find a thing, they said everything was fine, is there anything else to check?

checked the timing lately? compression check?
is your cat gutted?

im going to check my timing this afternoon but its set at 0*. I just had a new high flow cat installed in june. and no i havent done a compression check, i guess i need to do that one of these days. but other than the smoke the car runs great, and is a beast out of the box.

I had this similar problem. I replaced A.I.R valve. Solved that problem....