V8 exhaust

hey up my friends,I took both silencers off my v8 only to sound great,but in so doing after a couple of weeks there seems to b a bad backfire every so often and sometimes on start up it sounds as though it's running on 4 cylinders shall I go back and fit one of the silencers or is there something I can do to keep it sounding great,thanks,it's a 1991.110,v8.3.9 with su's on petrol and LPG

Personally I'd check the spark plugs frirstd

Hey up my friend thanks for reply but every time it backfires I take plugs out and clean them,nearly new plugs as well