After close to a week's driving, here is what I've notice:
1) Performance - the car got faster than when I first installed the Unichip. It is definitely NOT in my head. The car is actually faster. I don't have any numbers to show, but right when the needle hit a little below 3000rpm in 1st - 3rd gear (especially in 1st & 2nd gear), there is this "kick" that I didn't notice after the first couple of days of installation. The "kick" is like someone has bumped their car into your bumper from behind. Some say it is contributed by the stock ECM's learning/adapting to the new chip.
2) Boost spike - there is another thread in the Factory Forced Induction Forum that discusses this in length. I do notice, in 4th & 5th gear, that the boost level goes to ~18.X psi when I floor the gas under 75, 80mph without downshifting. Some has done the needle-valve mod (discussed in that post) that controls the spiking, but I'd want to hear from Mark from TurboXS directly before I proceed with the modification. Couple of us, including myself, have emailed Mark with the link to the boost spike with Unichip post, but am rather surprise Mark has not come out to give his valuable $0.02. Usually he is very responsive.