Doug's Muffler, Joy and Gratiot just past the railroad tracks.
I was working at Chrysler when the PT launched in 1999, and they had an issue with differentiation when they launched the car with a base and up-level naturally aspirated four cylinder. I remember them asking the exhaust guys to squeeze down the exhaust on the base four cylinder engine in order to make it a bigger jump in power to the up-level engine. So if he has the base engine, I would look at aftermarket to gain a few ponies.
-Geoff