I have a 2003 with a k & n cone filter and bluecollarbobbers drag pipe on there(it has a baffle in it ). jetted out the carb to a 152.5 main and a 55 pilot and im still gettin backfiring after turning off the bike. I live in miami florida where its pretty humid which i heard plays arole in tunning but im not to sure. I took the plug out for the fuel/air mixture and have it 3 turns out from close. that bike has about 6000 miles and she has been getting hard to start latley What could be the problem?

The bike backfires when you shut it down.....because you have shut off the ignition and there is no spark - while the turning engine is still sucking air through the carb and mixing it with fuel.  The fuel is then pushed into the exhaust and ignited by the hot pipe.

A lean mixture in the exhaust can make a louder bang than a rich mixture - but trying to richen up the mixture too much to eliminate the bang will make the bike run rich with poor fuel mileage, potential problemes with carbon fouling, and reduced cylinder and ring life if the excess fuel washes the oil off the cylinder walls.

If you let the bike idle for 20-30 seconds before you shut the engine off it might allow the exhaust to cool a bit.  You can also try pulling your fuel enrichement knob out a notch or two when you turn the bike off, or you can leave the bike in gear and feather the clutch with your left hand to slow the engine down faster while you turn off the kill switch with your right hand.  And as much as we like a high idle speed to help keep oil pressure up to the head at idle.....too fast of an idle speed can make the "pop" on shutdown much worse.

Blow out the cavity the plug is down in before pulling the plug. You don't want dirt and grit falling in the jug.