That usually tends to be the case with most cars that are still under warranty. I manage the performance department at a BMW dealership and we are a mod friendly dealership so no matter if you bring in a fully tracked out 335i or a supercharged M3 with full bolt ons, we have you covered. I wish this could be the same with other dealerships.

I'm sure any Lexus dealership wouldn't even want to touch my car with the twin turbos installed even though I still have power train warranty.

 

the e92 m3 SC is proven power with easy ECU tuning.....this lexus 2IS 3IS is not, not yet.
Engine tuning is the most critical and probably overlooked FI component, putting a big turbo and intercooler is just the beginning.

 

BTW, the N54 stock gets you 270 at the wheels, add a Tune + FBO you are at 370 at wheels, with E85 your are in the 415 range, meth 420..to 440 on STOCK engine and turbo......how much can you extract with the lexus V6?

the M3 e92 are 370 or so at the wheels stock, add ESS SC and you are in the 500s range...
again, what are the numbers of is350 V6 supercharged ?

the i4 (ie N20), CLA or the STi boxer are turbo from factory, and are easy to tune, jsut add boost and timing producing more power......not so easy with lexus.

i say this again, if you are chasing power, should have considered a better platform to start with from the factory.