I just cut out my pair of resonators and straight piped a 2.5" 4 foot long section in place of them. It gave it a quite bassy sound and my butt dyno says it really moves from 55-85 mph.
Then again I have only had this 83 300sd for like 5 days, it could have to do with the low sulfur I put in as opposed to the tank of b100 I had run through it