Blew a massive hole in my exhaust so I have replaced the empi single quiet pack back to the stock exhaust i.e. 4 into 1 header now gone. I thoiught the stock exhaust would be better for me because I kept smashing the empi on speed bumps etc becuase the van is so low. Now that the stock exhaust is on when the engine gets warm I assume after the auto-choke cuts out my van starts jerking and backfires. My old exhaust had air leaks from holes etc but the new ones fitted proper, I am right in thinking because the new exhaust is much smaller and that the leaks have gone away I just need to change the mixture? Is it something to do with the back pressure on my new exhaust effecting the timing? spent 3 hours under the van yesterday freezing my nuts off, thought I had done a good job and now I have another fucking problem to deal with. Help

Changeing your exhaust wont alter your timeing. seems you may have another fault somewhere.

Sorted in the end, the change in exhaust must have coincided with plugs/points on the way out. Did a basic tune up new plugs,points,condensor, timing, idle mixture setting and now sounding sweet and starting first time. Now lets wait for the next thing to go wrong