I bought a set of Flowmaster mufflers and installed them in place of the stock '90 mufflers.
Resonated like a bad dog at highway speeds in 6th gear.
The drone would drive you nuts.
It also burbled and popped on deceleration (which I didn't mind).
I put a complete Flowmaster setup on and the resonance and pop are pretty much gone.
Next step will be x-pipe in place of the resonator later when the weather warms a little.
Don't want to argue with the Smog Nazi's so no plans for headers or removing/replacing the cats in my near future.