I have a 1970 Ford Torino GT with a 351C and 4 speed manual. I have done a lot of work on the engine (complete rebuild... balanced, new cam, head job, new 10.7:1 pistons, roller rockers, new demon 650cfm carb, plus more) and would be happy to provide specs if it helps. My problem is that on deceleration I am experiencing a lot of muffler 'pops'. Not backfiring, the car runs great, just muffler pops. I cannot for the life of me figure our what is the cause. I have adjusted the carb to no end. I suspect something with the valves or spark system, although all components are new, of high quality and workmanship. As you can read, this is very perplexing... any help or guidance appreciated, from one rodder to another.