What would be better supercharge or turbocharge my 2006 Lexus IS300

Do whatever is allowed in your intended racing classification.

If you're not racing, is not it sort of pointless?

no point of doing that.save the money and get the new model !!!

Without a doubt turbocharge it. The supercharger will barely give u 350whp with lots of supporting mods. Get a T67 turbo from someone like Turbonetics or boost logic & u will never regret it. Keep in mind that the stock automatic can only handle about 300-320whp & anything more is playing with fire. So my advice, get turbo, BUT first invest in a good tranny. either an R154 from a soarer or MKII l Supra, a V160 getrag from the supraTT, or a built auto from someone like boost logic or sound performance. OR if you're really crazy & money loaded, u can get the sound performance 4spd TH400 transmission which is by far the best automatic u can buy that can handle with ease 1000+whp.

turbocharging would be better.

there are a lot of potential issues with aftermarket turbocharging .. it gets expensive very fast

you should consider purchasing another vehicle instead

Lexus IS300 is replaced by the IS350/IS250, is that what you meant? Anyways, there is no turbos out for the current IS but there is a supercharger made from BLITZ which is in stores. If you want a turbo, wait a bit, their in the works. If l were you, l would go with a supercharger for the Lexus IS.

Do not do it, you could end up with a money pit. On any car, once you mess with one thing you have to mess with another. Therefore you will be chasing your tail modding and fixing issues.

why would you want to do that, just wait for the IS-F to come out and you would have a V8 monster sitting at your driveway.

An IS-F will cost you less.