You really should take a ( good ) YouTube video of vehicle backfiring so the gurus on here can get a listen,, rather than go off your words..
Ok.
(disclaimer) we dont have emission checking at all where we live
The only things left of emissions is the charcol tank fume catcher thing and the PCV system,, car has never back fired, Like i said it has been his daily since April or May and he has put at least 15,000 miles on it ,,,being a high schooler in the summer and all.
The only thing other than the normal strip stuff off is,, we cut down and plugged original EGR valve unit so that we could use manifold with bigger runners , have a cleaner look and still have stock PCV hose location........The air pumps on the car and the parts car he got were both seized up..
this
into this and you can see most emissions are gone
Wanted to also say me and my brother both have Webers on our older cars and they work fine,, but had to fuss with them to get them right..