this has been discussed before on here..do a search.
I still have a goal of getting the Harrop supercharger put on my V8. But as it's stock 7PSI is what they recommend. Given mine i s a manual i will need a heavy duty clutch.
Pskhaat's pic on the pistons con rods is correct, so if you go above 7PSI, then you need stronger components.
There's heaps of info out there. And of course if you go above and beyond the capabilities of the engine as is, then you need to adjust the injectors, then you need possibly to consider either a piggy back ECU or a totally replacement one...and of course extractors/headers, custom exhaust, and if you're into the hi performance then you to replace the whole fuel delivery system coz factory wont cut it.
the info is out there, and its even on this forum (a nice twin turbo 4.7L is on this forum, albeit not in an LC/Lexus). You have a guy in Florida over there in the USA that does that. Here in Oz, we have a guy at bulletcars.com who's an expert in Supercharging the beast.
But, dont forget that you guys have the Tundra over there, which is raced, and you have a significant amount of knowledge on the 5.7....which is both raced and on the drag strip.
Any info on that, please email me
peter@loved.com as i am into that stuff!
cheers
peter