exhaust, missing, problem
 

I have a few questions, first I was told that I could not put 2.5 on exhaust on my 89 GT from the mufflers back. Also is there a 2.5in exhaust (tailpipes) premade by like flowmaster or Mac. Second I put a timing light on my car and I was watching the mark on the crank I reved the engine and the mark didn't seem to move much. I thought the timing should really advance when under a load. this might lead to my final prob The car runs bad when the air outside is cool it will miss and hesitate under no load situation, but when I hit the gass all is well.
Thanks for the help

2.5" exhaust will easilt fit

When you rev up the engine at idle there is no load on it and the timing will not move very much. Itsnot like the old mechanical advance units that moved with rpm. You mention that its worse when cold, possiblity of coolant sensor or ACT sensor. Check your codes.