OK, I personally did not see much difference between the suncoast tranny equiped truckthat I got to drive for a day and the HD rebuild trany I have. as far as the valve body goes, they both shift about the same so i think there is a far cheeper route to take when considering VB mods...
shift kit... $57 bux
http://www.transmissionpartsusa.com/...-00054931c.htm
DIY install... $0
pay a shop to do the install, most likely under $200 bux.
I have the suncoast VB installed in mine and it did weired things and never really met my expectations. Since the HD rebuild, shifting was ok but not what I'd expect (again with the SC VB). Tranny shop guy felt the trans-go shift kit would be a better setup based on his experince. So in went that shift kit over the suncoast kit. After some tweeking and dialing the VB back in it performs just as good if not better than the suncoast one (better IMO...) and if I did the install myself would have run me the $57 bux +shipping + fluid to get it done.
afraid of messing up your stocker? $200 bux buys you a reman'd one here...
http://www.phoenixhardparts.com/brow...andard-VB.html
if I knew what I know now and had it to do over again, for my everyday driving needs I'd have bought the kit and installed it myself, if I messed it up, chalk it up to a learning experience. Instructions are included though and I can read so it should have been no problem. As for the tranny's from the big boys out there... I'd bet they're using the same stuff that went into mine, local builder, local help, customer satisfaction.
Remember, I dont drag my truck but I do beat on it some and it does get used off road some as well, the route I described would have worked for me and my needs...
hope this helps.