360 la headers & straight pipe

Assuming your headers have 3" collectors, and your using reducers for the 2 1/2 pipes..... ditch the reducers, put on straight 3" tubing.
Just be advised, most people (well, me at least) think an uncorked stock low compression motor sounds like ****, besides being too loud.
Fast and sneaky quiet is MUCH better than slow, and loud. (and I have definitely been both.....)