Sorry for getting this thread a little side tracked, I know this thread is about Dynomax mufflers, but because ATR haven't been around for many years, wanted to show what the ATR pit bulls look like to those who have never seen em before.
If you can find some used ATR Pit Bull turbo mufflers, grab em! These were offered in both aluminized steel & stainless steel. Of course, stainless are preferred as they will outlast the aluminized ones.
Here's some pictures of an old set I used to have until I upgraded to a pair of NOS (still in the box) stainless ATR pit bulls that I stumbled across. They don't appear often, but do become available once & awhile. Just gotta keep your eyes peeled.
You can see they are a "straight thru" design, which offer optimal performance on a turbo car as they offer little to no restrictions (but do drone a little at a certain rpm / frequency).