Hi all, I was faced with these concerns before I supercharged, I think the engine is advanced but has been lowered in power, the car is fine with the compressor I spoke to tte and it is perfectly ok. The main point is that lexus (japan) dont like their cars played with, they tried to put a stop on superchargers at first. Becuase of this no one makes any engine upgrades for induction, chips etc. In the USA where the IS300 rules they are doing all sorts (swift racing technologies). They are getting quite a few hp from induction kits.
Hopefully this will change, some Lexus Dealers do think the supercharger should be an official add on.