All I got to say is that since I am using the stock SVT intake now (pending other intake mods :D), truthfully, cold sounds raspy, not bad, but still there... warm, it sounds like a Bassani on crack... hehe... I think it sounds good... and I hate raspy exhausts! There is droning, just like any freeflowing exhausts, but is only about as loud as a res cut SVT exhaust.
But I've been thinking about it, but I dunno if I can get my muffler place to produce them... But I will ask. After some revisions in my setup (H-pipe to X pipe and a couple other adjustments) I think it'll be ready to blueprint and MAYBE up for sale...

I never want to sell anything that can be done cheaper on your ownm but if people are interested, I'll start setting it up...
A few other people in MI did their own setup, so all that matters is personal preference...