I am planning on a K@N cold air intake with filter next. It supposed to increase H.P. by almost 14.
save some $$$ and make your own, its pretty easy. Trip tp hOME DEPOT +$20, and www.hightempsilicone.com
I sometimes worry about the transmission, as it makes a high whine when it's cold. I have heard of problems with the standard Impalas, but I think the supercharged units have a stronger tranny. I have to research this....I've had my SS for 3 years and it never gets boring. I love it!
IIRC the only diff between the 4T65EHD and the 4T65E are
1. gear ratios 3.05/3.29 for N/A, 2.93 for S/C
2. from the diff out (pass side axle, diff, parking & sungear, etc)
It also has a larger TC/Flywheel, and lower stall speed on the TC
The trannys hold up very well on an UNMODIFIED (CAI/FWI/PCM still count as unmodded) car, once you go to smaller pullies, cam/rockers, etc they runinto issues. I beat the living snot out of mine, and the trans is only slipping. The only thing i have managed to break on the car are one pass side cv boot (burnouts @ the track most likely), and a wheel hub siezed on me. My clutches are slipping, but have been for oooo, almost a year and a half now
Been putting that off till i finshed the engine build I'm working on. No sense pulling it twice
if you ever need trans work done, i recommend http://www.tripleedgeperformance.com/
but being in cali, its a bit of a drive for you