All these truck really need is a tune, can get em in the mid/high 12's w/ tune only through the 1/4 - that IS PLENTY fast for a 1/2 ton offroad pickup, & not that far behind a TRX, I believe tuned Raptors can move as fast 4.2 0-60mph, although i think 4.4-4.6 is more common
After that the only real power adders before you get into stroking the motor (which people have done) would be turbo adpaters, downpipes, & of course larger turbos - check out Gearhead tuning for those, I think you can do some ethanol/methanol setups too
At the end of the day though no single mod aside from a tune is going to have as big an impact on overall performance
Better intercooler if you live in a warmer climate and/or will be really pushing the truck hard offroad regularly - and in the case IMHO a stock mount location unit is much better than a big "FMIC" that can be seen through the grill & blocks the engine rad - there are different schools of thought on that though, an IC won't add power but will help the truck to keep producing that peak power consistently