88 4runner more horsepower! HELP!

Just got an 88 4runner with a 22RE. I've heard that replacing the camshaft will help gain more horsepower. Does anyone have any other suggestions other than converting to a 6cyl. (at this time $$ isn't available for the conversion but it may be a possibility later)

Better carb, bigger cams, better header, head work.. The list goes on. Need specifics?

Would be appreciated.
Thx!

Good place to start:
http://www.downeyoff-road.com/EngineComponents/index.htm

http://www.performanceproducts.com/default.aspx?referer=1828

http://www.toyotaperformance.com/efi_systems.htm

http://www.doaracingengines.com/4cyl.html

http://www.lcengineering.com/

Thanks!