i am eventually planning on getting a lexus is300. im planning to add a cold air intake, headers, remus exhaust, and maybe an intercooler/supercharger. is this practical? and more importantly, is it street legal and does it meet emissions standards in southern california. is it going to be too loud and am i going to be pulled over frequently?
also, what is the average cost of one from a dealership and one from a want ad(or something like that.)
also, if some are street legal and meet emissions standards and some aren't, which companies make the street legal ones?
also, if some are street legal and meet emissions standards and some aren't, which companies make the street legal ones?

what the fuck was spammer blabbing about? he doesn't even know what an IS300 is, let alone comment on it. To answer all of this, the only way you will fail emmisions is if you get a stand-alone ECU when you go forced-induction. Going MAP ecu will get you to pass with flying colors. Make sure you don't delete any of the O2 sensors when you do this or if you do get a O2 simulator.

Just placing the car on the side, like any car. Now these days, it takes a lot to get it really modified or to obtain a good noticeable performance change.

Car companies push these engines to meet emissions and squeeze every bit of power they can get and keep it drivable with good riding characteristics. No much room to improve unless you suffer from lower gas mileage, smog increase, or is not smooth running with a narrower power band. The best bang for your money is a computer reprogram.

You want to make more mods that will give you more, you have to move from California, like in the Midwest, they do not have emission tests. Some has just safety inspections.