i have a 89 iroc with a 350 tpi and i just installed some headers and true duals. one 2 1/2 pipe exits before each rear tire and there is a glasspack after each header. now the problem is on the drivers side a popping noise comes from the pipe while in park or when i decelerate, but not while idling in drive. its an annoying poping noise and want to get rid of it. the passenger side doesnt do this, it has a real nice deep rumble as does the drivers side but has the popping noise along with it. any help is appreciated.

 

one more thing, i was thinking maybe an h-pipe would solve this problem. or would it just make it to where you can hear the popping noise on the passenger side too. by the way the motor only has about 4000 miles on it so i know its not the valves or anything of that nature.

 

I had the exact same setup when I ran true duals on my red 91 RS I onced owned. A weird sound. I thought it was the of the glasspack itself. A muffler change could change it maybe. Anyways I sounded awesome when I got on it, but the bad thing it pinged badly. I think I killed too much of the back pressure. It ran better when I went t o a full exhaust.

 

Thats one good thing about duals - you can identify what cylinder bank is acting up

I'm guessing but it sounds like raw fuel is coming out of one of your drivers side cylinders and explooding in the pipe- your car is running a little richer while in park and decelerating and only causing the popping then - see what the O2 sensor voltage is when its happening -I'd check the plugs wires too-