the oem midpipe might be a problem. i don't know the FX real well, but you need a free flowing exhaust to make this kit work. You'll have the same issues everyone with the kit has, boost dropping as the car reaches redline.
I guess this will be a good thing for me
The other way is to sell this thing (if I can) and pay about 3000 more and get the stillen but that thing sounds horrible!