well, the most common and esiest (even most logical) is the sr20det engine swap. its a 2L DOHC Turbo motor that drops right in with only minor problems such as some hoses (re-routing) and ectending some wires. dont need new motor mounts!!! (unless you got a motor with lots of miles) the motor produces 205hp and 203 torque at 7 psi!!! so there's lots of room to grow to get more hp. check out
www.srswap.com for looking at parts n prices.... you can even email the guys for help or qestions. happy huntin'