I am at 210WHP without the nos and 300whp with nos.... WHP is different then HP or BHP... My torque numbers are what really increased, and torque wins races....
I would say your 97 SC400 in stock form would probably dyno now at 185whp and or 250bhp if your lucky. Remember the car loses power over the years so it will not dyno like new as advertised when it was first rolled off the assembly block...Electrical, and other stuff, etc.. wears out and you lose some horse power over the years...
With headers you can kiss your smog checks good bye... The rest of the exhaust mods, highflowing cats, mufflers, and larger exhaust piping will still allow you too pass smog... Headers mess with the O2 sensor reads and throws the check engine light... With the S&S Headers I cannot pass smog..
With nos you can pass smog, and with a supercharger I dought you will pass smog, but I am not %100 sure... Depends on the supercharger, tuning and how it set up... I have never seen a custom turbo on a Lexus pass smog either...
Exhaust mods (except headers), torque converter, and intake mods will not effect your smogs...