thanks for that teddy,
i work for southern hightlands toyota in moss vale, nsw.
I'm thinking i will probably use a silver top 20v with the factory ecu.
should have plenty of power for my class.
rules say you must stay under 1600cc calculated capacity, so if its got any form of forced induction, your engine capacity is times by 1.5 (i think).
so a turboed 4age or a 4agze is out of the question.
for improved production class you can use any engine built by the same manufacturer as the body. So in my case, any toyota engine.
so the 4age seems the most logical answer to me.