DEFINITELY swap out the plastic steering linkage. The plastic bushings wear our REALLY fast!!! That's usually a first upgrade!

Pipes. A buddy of mine and I tried a few different pipes. We found the best one for torque and HP to be the AE pipe, coupled with the big-bore header (I think you can get it at hobbyetc dot com). The really woke the truck's pee pee .15 motor up. We installed .12's later in both trucks with the same combo and man, was it fast!!!