Well, I want to go with a custom install, and I'm looking for a muffler that will perform like the APEXi PS Revolution, that is it has a valve that opens when pressure is high, and "muffles" only when you are part throttle/ idle. However, the PS Revolution comes in cat back only, I want a standalone muffler.
Anyone know of anything like this?

Well, exhaust shop offered to do customer, but said there would be an advantage with mandral bent piping and suggested ordering stuff that has been engineered for performance. With that said, I think I found something pretty cool, as far as drop down pipes go.
This is coming soon for Evo X:
http://www.quicktimeperformance.com/Downpipes/index.php

here is a remote for that:
http://www.quicktimeperformance.com/Controller/index.php

That is what i had on my SRT-4, just a different maker. Also that switch is a bit a huge for my taste. I like a small descret switch. But having an e-cutout is great because i can be quiet when i want, and then if i chose to go hard, i would open it up. Nothing like the sound of an open turbo!

Ill have to look it up but you can also get boost activated versions of the E-Cutout... It works on a solenoid that opens up the exhaust cutout once a certain PSI is hit.

So you could have it set to open up only on boost past 12psi and anything below it stays closed.

The DSM crowd is really big on this version, I just dont remember the manufacturer that had these the last time I saw it.