ansa exhaust How to improve the flow on ansa exhaust. or, can you?

Yes.  It's a bit of work.

There is a technique to "gut" the mufflers, and reduce the tubing in the can, then weld them back up. 

Here's some ideas to peruse...

Seeking feedback regarding new mufflers and their effect on EXHAUST DRONE | The De Tomaso Forums

Rocky

I know there's Not much room back at the Mufflers, but has anyone tried some kind of a J Pipe to help with the Drone?

I cut open the top of the cans on my first Pantera and reduced the baffling inside, and then welded it back together.  It greatly improved flow of the exhaust.  It also made the exhaust much louder.  Once back on the car, you could not visually tell that anything had changed.