Pissed off with motor, want to change

Yes, I broke it in at 2500 rpm for a half hour. Comp Cam XE268H cam and lifter kit. Would a ballast resistor cause a backfire? I thought they were more start / no start problems. It ran perfectly until I went in the car wash. Drove in fine, backfired driving out. I am down to compression check now. Hoping for the best, fearing the worst.

Bill, would a carb cause backfiring only on exhaust? If it is carb or ignition related, I changed everything in the ignition, so that leaves the carb. I kind of believe flat lobe or bent valve, however.