not spooling right

[lazysk8er2]

ok heres the deal i got an s13 with an sr swap done a while back. the harness was hacked so i tried to fix it but it was a no go so the car sat for 6 months. recently got it on the road with a brand new harness and done professionally at a local 240 shop. the car has a t25 with a welded external wastegate on the stock manifold. i have a hks front mount walbro fuel pump and a bunch of other goodies. stock ecu and no tuning devices. it ran fine before but would have to replace spark plugs often.

ok so my problem is when the car is warmed up and im driving at around 3k and i start to push on the throttle the car rappidly backfires, sounds like machine guns. but when the car isnt fully warmed up it doesnt do that it boosts fine. currently running 6lbs of boost. replaced the maf and someone said my wastegate may be done or acting up. im gonna take that apart tomorrow and test it at the shop. also gonna look at the coil pack and recheck the gap on my plugs. anyone got some help.