ok now when i shift gears im getting bad backfire almost every time what can stop this

 

what mods do u have on what type of car? This will also help us to tell you how to or not to fix it. And how bad is it.

 

1994 honda civic ex vtec i have headers intake and one of those tin can mufflers

 

i have the same problem but its occasional. Make sure all your header bolts are tight and also all the bolts down the exhaust. You could possibly be sucking air in if they are not tight. Also check plugs and wires, cap and rotor. On my car i have header downpipe no cat and a straight through muffler.....i was told thats wat is causing my backfire

 

What type of muffler do you have: a perferated core or louvered core? Also how wide is you exaust pipe? Do you have a tri-Y or 4-to-1 headers?