Assuming you want to stick with a Toyota engines the easiest options are: - stick with the 4EFTE, decent power can be had out of them - upgrade to a 5EFE (1.5) and turbo it, or one step further the 5EFHE Or if you fancy doing a bit of hard work: - swap a 4AGE 20v in there (1.6) they have around 160bhp as standard and some come with ITB's - 4AGZE or 4AGTE, the 4AGZE is a slightly different version of the 4AGE with a supercharger, but you could change to a turbo - and being silly now you could use a 7AFE bottom end (1. with a 4AGE/GZE top end - and another option is the 3SGTE engine (2.0) which is found in the MR2 turbo and Celica GT-Four. So to answer your question "what 2.0 could I use", you'll want to be looking at a 3SGTE swap. But really a 5EFTE with a fully forged rebuild, some headwork, and a decent turbo setup should easily give you "enough" power.