avon

I've got a 4x4 Subaru wagon, 1.8l carb with the 4wd hi/lo 5spd transmission. My mind has been wandering and I've been thinking of ways to get a more powerful vehicle. I've been looking through this site and I've got some questions: What engine / transmissions work the best? Do any "bolt in"? I'm assuming that custom half axles would need to be made and the rear driveshaft modified? Anybody played with the megasquirt system instead of sticking with the subaru ECU? I'd like to get as much information including pictures of people that have already done this so I can make some decisions. Thanks in advance.