I have TTI 1 7/8" race headers. I have more clearance than I did with the 727. Removing/reinstalling trans and headers is a breeze with the bellhousing being its own part, instead of being cast into the trans.
I run 3.5" mufflers after the collector with turn-downs, no X-pipe. I honestly think their full system would fit, since TTI says their x pipes clear TKO-500 and TKO-600 transmissions, which are larger.