TBS w/ 2 shims is a lot. The needles (and shims) have the most dramatic impart of the fuel delivery at mid throttle. I'm running TBS with no shims. I was using stock w/2 shims.
Exhaust pops on decel "usually" are from a lean condition- either from jetting or a leak in the exhaust system introducing atmospheric back flow (fresh air).
What size pilot are you running?
