nytrdr24
+1y
domestic v-6's & v-8's are nice if you want to spend the time shoehorning them in the truck, but not to nice on the gas mileage you'll get, plus the extra weight of one, on the upside, the oem & aftermarket parts availability of one are endless....the saturn/pontiac/gm ecotec is a good idea, theres a guy with a honda s2000 engine in one, several guys that have done the kia swap which is pretty easy, and with some time & money could be made into an economical 4-cyl performance motor. the rotarys are nice, and several have been put into these trucks aswell. they will wind up tighter than dick's hat band, and can put out enormous amounts of power from a small package, but they aren't notorious for having much torque.....best bet for you is to sit down figure out how much $$ / time you want to spend, also what your looking for in the truck as far as being pracitcal for your useage, and then go from there......
I myself would like to see something on the exotic side (thinking outside of the box) like a wrx or porsche engine or a small turbo diesel put in one .....gobbs of hp & torque, with the benefits of being light weight and fuel efficient, not to mention just kool as heck to see in a mazda!!