[95/GT/5.0]

I see you installed some new exh. Did you remove your catalytic converters?If you did and you still have the smog pump and air tube connected.This is your popping from the exh.The smog pump, pumps vented vapor from the fuel tank,etc. and burns it in the passenger side cat which have probably been removed.You are actually simulating an exh. leak,the smog pump is pumping cool air into the exh. pipe.What happens when you have an exh. leak.It pops back thru the exh. pipe.You can buy a idler pulley to put in place of the smog pump and use all your oem's or you can get creative as I did and re-routed my belt eliminating 14 inches of belt and the smog pump( w/ slight modifications).My 1995 5.0 popped thru the ehx. after installing an offroad H-pipe and flowmasters.Eliminating the smog pump and air tube was my fix.My smog pump and solenoids are still connected,just the belt doesn't go around it anymore and I removed the air tube and capped both ends.I assume you don't have to pass an emissions test where you live.Just my 2 cents.