throw in a ford or chevy motor they are a dime a dozen and parts are cheap toohey you can get a crate motor rated at 400hp!!
or more...wait is yours fwd? if so never mind what i said and throw in a 3vzfe or 1mzfe and supercharge\turbocharge it. or the 4 cylinder method would be 5sfe(5sfte),3sge(3sgte),4age(4agte),7afe(7afte) don't limit yourself to a certain engine and go for it just make sure to get a "donor" that way you'll have all the parts you need
you guys don't realize... SR5's are good candidates for upgrades! At this day and age, most GTS's are worn out and tired, with lots of rust and chassis fatigue. I find that SR5's probably fare better because the owners don't push those cars as hard (or just simply can't, lol).
Anyway, if you wanna simplify things and have a balance between budget and power, get a 4AGE, put on some Side Draft Carbeurators with intake manifold, some streetable cams, ignition box, play with some at home SPL porting and polishing with port matching, a timing light and a long straight road with no side entrances to do some tuning.
You won't have GOBs of power, but a nice balanced power upgrade and a symphony of air trumpets.
Trust me, after putting up with a boosted 4AG(ZE) for so long, you get pissed at all the parts you break and all the money you spend because of tired parts that simply give up after subjecting them to more power.
Go the easy route and have fun. You don't need a lot of power to get sideways and besides it keeps you outta trouble.