Auto Racing: About exhaust pipe please..., throttle body spacer, performance muffler

Question
Hi, I have a stock 1997 jeep cherokee 6-inline 4.0L engine.
I want to make my engine breathe well :) so it will be faster.. What should I do to my exhaust pipe and tail pipe ?? increase diameter or decrease ? I want to do it in a welding garage.. Thanks.

Answer
There a couple of things you can do. First is get a low restriction air filter. Second, see if a throttle body spacer is made for your application. Next I would look at replacing the cat with a performance free flow unit. Then I would install a bigger diameter cat back system that includes a performance muffler. Dynomax has these kits and they won't break your budget.
Hope that helps. Let me know.