Are we talking about the MKI or MKII MR2? I'm not any good at tuning, but somehow I arrived at a decent setup on my MKII. I tried a few tunes that I found online and none seemed to work well. I tried that spreadsheet that's supposed to give you a decent starting tune for any car. I might have even tried a tune for a totally different car, but through some series of events it now handles decent. I've been running it in garris's PCP series and it seems to perform well. This is at 450pp and SM tires.
As it sits now, the rear end is fairly tame and predictable under braking and corner exit. Turn in isn't stellar, but is acceptable. There's a little mid-corner under steer that is annoying. It's kind of hard to explain, but the car turns in ok, then starts to push a little, then regains composure and turns in hard again. I bet someone who knows what they're doing could make it really nice.