hi guys! i just joined up, figured i'd check to see if there was an impala community. :)
anyway, good resources on impalas:
http://www.naioa.com/ (VERY active message board, very knowledgable owners)
i have a 2001 impala 9c1 (police package) which i have done quite a few modifications to...HID driving lights, a FWI (fenderwell intake, slightly different than a cold air intake), poly motor mounts, GM molded splash guards, removed the resonator, ventvisors, a skid plate, kyb gr-2 struts, normal prestone coolant, and a bunch of other stuff.
my future plans are replacing the stock certified instrument cluster with a monte carlo SS cluster (with tachometer, volt gauge, and oil pressure gauge), installing a drivers information center, getting the u-bend taken out of the exhaust, and getting the DHP powertuner. at some point i may get a ported throttle body, but that's after i do all the other stuff. ;)
catch you all around!