Things that would improve HD

[captaingrim]

IIRC from the 1Up interview, in the order of 400,000

Woah there neddy... Try 40,000 instead!

I've notice that some graphical effects are gone from the PSP versions. The main one for me is when coming out of a tunnel that there is a burst of brightness then normalizes. Or going in to the tunnel it is slightly dark, then adjust to normal.

The effect that you're describing is called tone mapping. HD does do this, but it can be a little subtle in places so you've probably just not noticed it