i got turbo why am i backfiring so muich when im shiftin at low rpms such as 300 or could it be there is too much fuel goin through cuz i got the msd inliune fuel pump[ along with my stock intank pump and my vortech FMU..,should i take out the msd pump??? help

 

I backfire too at normal rpms during shifting. I have stock pressures too, so I have NO idea why, while out of boost it SHOULD run like stock....