I put the belt on my AIR Pump this morning since I took it in for emissions testing. Well when its hooked up taht thing backfires like mad. I mean like flame shooting gun shot rivaling backfires. Without the AIR pump it just crackles a little but with it is full on drive by sounding backfires. I actually saw little children run when I just went for a drive and it surely sounds like crap. Sometimes it sounds like it might be misfiring too. I just checked and reset my timing to 4 degrees(factory for my 305) it was at 6 degrees. Still does it. I was thinking that maybe my vavles are badly adjusted and slightly open making it so the air ramming in forces into the exhaust valve and makes it misfire then load up on fuel. Sounds good in my head not sure if its the problem. Anyone have opinions on this matter?