I forgot to tell you that there are step-by-step instructions for the Mac at Mustang Worlds web site at
http://www.mustangworld.com/ourpics/fcar/hpip1.htm
I used these instructions to remove my stock H-pipe and will use them to install the Pro Chamber when it gets here. Great pictures and very detailed instructions. Highly recommended. Check it out!
Oh yeah, and a new X/H pipe will make your car louder as well.