You may want to get the BBK just to keep it all in the family. Sometimes they seal better when they're the same brand. Otherwise, my vote is for the ProChamber, for both power and sound. I had one for two years, and wish I still did. I'm curious with 5.0GT on this one- WTF do you have under the hood to justify that exhaust? If you don't have at least a heavily built 351 in there it's going to be a complete waste, you'd make more power with a smaller one. Those sizes are optimal for more like a 393 stroker, or 20+psi of boost.