IIRC, the additional power came from a more aggressive ECU since they have a higher octane fuel over there and they do not expect engines to last nearly as long as we do. The replace engines by 50K miles for emissions reasons.
Drifting Dane, do you have an NA and are looking to swap?
Unless you are completely in love with your particular MR2 or you have a lot invested in it, you may find it better & easier to sell and buy a turbo MR2.
I am personally not into swaps, unless you are doing something that you could not buy (like a V6 MR2). If you can buy it, buy it. Your swap will never be as good as the Toyota build real-deal.
You may find some helpful information at
www.paautoracing.com.
Talk to Dave there and tell him I sent you.
He specialize in clips & swaps.