This man speaks the truth! That's a very good run down on what exists.Just to help you out here. In the US the second generation MR2 SW20 was sold from 91 to 95 that's what you're looking for.
The V6 engine in the ES300 isn't specific to the ES300 it's the 1MZFE it came in camrys, avalons, siennas, solaras, rx300, es300, and highlanders. The 1MZFE can be had in non VVTi and VVTi versions with VVTi being more powerful.
The Rav4 V6 is the 2GRFE which comes in numerous toyota and lexus vehicles, it makes a substantial amount more power than the 1MZ even when the 1MZ is supercharged.
It's going to be very hard to find a turbo 2GR MR2 for sale there aren't many out there much less for sale and they're dangerously fast.
Yes, for most folks, a stock 2GR in the MK2 chassis will be the quickest car they've owned. It's a very satisfying amount of power for the chassis.Are you saying that the stock V6 has plenty of torque and HP power without the ned for a turbo or supercharger?