I saw an X-power run on a CA SO, and it made less hp by itself than the guy's EZ made by itself. I wasn't impressed. Typically the SO trucks respond extremely well to power-adders. I'm not sure if the X-Power Plus is available for the older trucks.
AKRAM on DTR (I believe it was him) had a BDDL on his truck with a rail pressure gauge. It did not change pressure on "tow" mode, added about 1k on "performance" and 2k plus on "extreme. "
If you call Bully Dog and talk to three different people, you'll get three different answers. I've heard directly from them that the BDDL uses no pressure at all. I've also heard from them they use pressure only on "performance" or "extreme," and I've heard they only use pressure on "Crazy Larry. " Choose what you want to believe, but I believe what AKRAM reported.
I'd suggest waiting for the Smarty to come out. It is advertised as being undetectable. Bully Dog originally advertised it was undetectable as well, but it turned out to be untrue. They removed that from their website, along with the advertisement that they store your "stock" settings before downloading their program.
If you talk to those who are in the know, they'll tell you that the memory can only be upgraded, it does not allow the info to be read. So bottom line is you get whatever stock program they decided to load their box with.
That said, I think their stock programming is remarkably close to what my truck was stock. I dynoed within 2hp with the Cummins stock program and the BDDL "stock" program.
I believe the FASS that TST sells is the lift pump replacement.