Just had my 4" turbo back system with cat delete put on today. Paid my local muffler shop to install it for me because I've got no way to raise the truck! I've already installed the Superchips on high setting a couple of months ago. My F-250 is a 2wd S/C automatic with only 60,000 miles. It seems to have more power all the way through the RPM range and shift a little more crisp and predictable too. Revs way quicker all the way through too. The sound is pleasantly lower and not blaring at all. The turbo is WAY more audible and seems to come out the tailpipe. Cool sound. The downpipe is 3" and expands to 4" where the cat used to be right after the downpipe ends, all 4" after that. I even put the 5" chrome"fart can" tip on for the bling-bling boys in their clown cars to be envious of! I haven't had enough time to assess all the difference it has made yet or had any milage readings. Milage will suffer as I keep my foot in it too much at first! Time will tell but I like it already!!

 

If you think a 4" system with a 5" tip is a "fart can", I won't ask what you'd call my 5" system with a 6" tip.
I'm glad you like your setup. Now to optimize it, you should consider an intake. My vote would be for a TYMAR. Enjoy your truck.

 

a fart can is something like a 2 inch pipe going into a 5 inch tip, like rice boys use