I just got plates and insurance on my Tracker.  Its a 92 4x2.
I picked it up late year & had to fix the crank gear & then swap the head because of an exh. valve not sealing.
I also installed a header.

I have just been driving around town under 45mph, but the tail pipe is hot all the way back at the rear bumper.

Do I need to change to a larger pipe (its 1 3/4 now) or what.  After I get new tires on the rear I was going to get all new pipe from header to tail pipe because I don't like the way its ran and I don't like the muffler thats on it.


Also when I get on it or let off the gas it wants to goto the side.  I have driven trucks with "lockers" before and they don't do that.  I have also driven open diffs & they don't do that either.

Its almost like the axle is moving, but I can't find any lose parts or bad bushings. 

Any ideas?

And Exhaust yip is going to be hot no matter what. Check your alignment, and breaks, also tire preasure for why it might be pulling to one side.

Warm yes, but not hot enought to melt the rear bumper.

It only pulls under power or when I let off, not braking.  The rear tires do need replaced & should be done this weekend.

You might check to see if you have a brake dragging on that side.  Does it make any noise when driving down the road?

No noise & brakes are OK.
If it was a brake it should pull all the time, not just under power or when I let off the gas.

I will still jack it up to make sure.

Actually it is entirely possible for a brake to be dragging and cause this problem, without the pulling being there all the time provided the brake in question is on one of the drive wheels.  It's not about the drag from the brake as much as it is the difference in torque caused by the drag combined with the differential action.

Other possible causes - alignment (also mentioned in the first response) - any defect in the suspension or steering that causes looseness can result in enough movement to cause the car to change direction, and frequently there will be movement one way under acceleration and the other under decelleration.