[Formulajones]

Cadillac quiet and performance is a tall order.

I agree with Scarebird though, you'll want the largest set of Dynomax mufflers you can fit. The 20" case Dynomax turbo mufflers are probably your best bet. The Ultraflows are a little louder but still very pleasing by my ears.

They are probably the best flowing mufflers out there while creating the least amount of noise.

I prefer to run X's on all my stuff and don't notice any significant sound differences as long as I'm running the Dynomax mufflers.

What I have noticed though, switching 2 of the cars here back and forth between ram air manifolds and full length long tube headers, is that the manifolds actually produce a noticeable increase in the noise level out of the tail pipes, especially through the mid range. When long tube headers are installed it quiets things down quite a bit from 2000 to 3500 rpms, especially noticed during cruise and light throttle. I actually thought it would be the other way around but apparently the scavenging affect of the headers helps. The manifolds package a lot nicer though.