There's no bug in HP Tuners. HP Tuners has maybe 10% of the total parameters in the ECM defined, so I've had to go hunt down the appropriate things myself and change the values to make things work. I'm working with HP Tuners right now to develop a patch to the operating system that'll enhance functionality, and that's what I'm waiting for before a public release of this. They agreed to do it because I can provide memory addresses and clear descriptions of what needs to be done, but I have to wait for it to get processed in their list of other responsibilities.

Yes, I have a low side. The car currently only has headers and the GM airbox along with a flex sensor because it is foolish to change a ton of things at once and expect to accurately find what tables/values need to be defined and how they should be adjusted. I have the low side set to trigger at 63 g/s of fuel flow. With the aux pump disabled, I would start to see a VERY slight drop in fuel pressure around 6400rpm on E65. A truly stock car can probably run E85 without needing an aux pump, but any mods after that will definitely require it. I'm working on developing a specific calibration setup for the low side (in the ECM) that'll make things operate nice and predictably.