Yes, the car is heavier than the previous generation, but only by 15 pounds (IIRC).

The car could be lower, but that is what the aftermarket is for. For the average consumer (not the 1% of enthusiasts) the car is better with a higher ride height. Between the springs available for the '97-'03 (G8) GP and GMPD parts that will be released, I think the lowering "problem" will be taken care of.

I agree that a beefier tranny would be nice, but the 4T80E is too big to put under the hood without some major changes.

As for the GXP fascia....the closest thing available are the nickel-plated grills and rear spoiler available from the dealer.

As for mods, depends on what you "normally" do. The G8 pulleys will not fit on the new GP, but there are new ones in development. The new TB is already MUCH larger than the G8 TB. The intake can be modified. I'm not sure if the G8 headers will fit. The exhaust systems currently available will fit on the new GP. What else?