2009 rk stage 1 fm a/c, PVC, v&h headpipes and turn down exhaust. Bikes got 20k miles and just replaced tranny fluid, oil, primary oil, and adjusted clutch and clutch pack....just recently the bike has a hard time starting... At first I thought it was the bike was too cold but even after I run it for a while it will do it time to time... It doesn't do it every time and after the bike starts it runs great... Right when it starts the exhaust let's a big pop out the exhaust and sometimes it backfires through the a/c when it has these episodes where it won't start.. Is there something I should really be worried about?