[backfire through airbox]

problem solved, spark plugs where shot. for future referance

[backfire through airbox]

hi, i recently fitted the G1 link to my99 subaru. i am experiencing a backfire through the airbox on full throttle at around 4200rpm only when i run hard through the gears. sometimes in 2nd and sometimes in 3rd depends on the load. where am i going wrong? pls advise