[jpg69bird]

My 76 Trans Am 455 starts and runs great. One flick of the throttle to set the choke and it starts right up without stepping on the pedal. Idles like a rock at 750. A few years ago, I took my time and tuned with a vacuum gage getting the carb and timing in sync as well as I can. Engine is completely stock internally, with a stock Q-Jet, recently rebuilt to stock specs. I don't think it's ever been apart.

The current exhaust is the stock logs, with a small aftermarket dual exhaust (no H or X) and a single cross-flow, dual in-out. This was put on by a previous owner, so I don't know the details. Looks to be a crunch bent 2" exhaust at best, I can get my fingers around the pipes at the bends, no problem.

I have a set of HO manifolds and the 2-1/2" 89021 Thrush dual with H-Pipe system ready to go on in the fall.

Will the engine need timing/carb adjustments after the new exhaust is installed?

If so, what direction do you typically have to go (advanced/retarded, more or less fuel at idle)?