I seem to the be only person that is using a Haltech 2500 on an NA motor, I've installed a Bosch DBW throttle body to the OEM intake manifold and am having problems maintaining AFR even with the wideband o2. It will run extremely rich at idle and up to redline, but under load it will go extremely lean in the 20s and i'm essentially having to rev it over 4k and feather the clutch to get it up to speed. I've read a few other threads of about the butterfly, it seems removing the vacuum to it is supposed to have it remain open, i've noticed no difference under 4k with the vacuum line to it plugged.
I'm hoping someone here has had luck using the NA manifold with Haltech, and if they happen to have a tune for it.