Backfire after 248/232 cam swap

[240RB1]

when under wot type conditions you can here little explosions in the exhaust what can this be?

94 vert 5-speednew knock sensor 284/232 camstiming set at 20btdcnew ngk plugsnewer plug wiresz32 fuel filter full 2.5in exhaust to a 2.5in high flow cat to a 22inch resonator to a thrush turbo muffler

when it "backfires" it seems to lag really quick but when it stops its all better. it just started backfiring after my cam swap today only under wot pulls

[90gtpony]

Sounds like it could possibly be the timing. Throw a timing light on it and see.