The bottom end is basically bullterproof as it is steel.
The normal tune is stage 1 around 270/280 bhp, which can be done with std injectors, normally as said yellows on a 2wd sapph, it consists of CHIP/-31 ACTUATOR/any exhaust and air filter swap.
Stage 2 next about 300bhp just a stop gap before stage three.
Stage 3 around 330-350bhp, similar torque. Same parts as stage 1 but also with a 3 bar map sensor as boost will be above what a std 2 bar sensor can read.
There are stage 1, Norris chips that will give similar intial torque to the normal stage 3 chips called gunship.
A VERY effective mod on the head is to de shroud the inlet ports by the valves, leaves the same size for port velocity but gets rid of awkward angles, makes a world of difference, with ability to hold max torque past 6000rpm then, as well as boosting earlier and harder, so much more flexible.
Above this standard type mods, there is pretty much anything you want.
tabetha