SVTFAN09

Hey guys just got my ls back loaded a little start up tune to get it going and noticed you can hear the car backfiring through the exhaust idle, at first I checked to make sure coil packs were connected properly, checked my plugs, they were fine , I'm ruling out it either has to be a fueling problem or a carburetor problem. I ran somewhat the same timing curve in my last motor and had no problems this is the first, what do you guys suggest or speculate it could be

Pop N Wood

iTrader: (1)

Exhaust leaks.

brandon6.0

iTrader: (32)

burnt exhaust valve? checked compression?