where to start
 

my bro has a 91 t2 and wants to sup it up where should he start:)

he and you should read the FAQ for FC found at the top of this section before posting for the reply to that question

Start with making sure the car runs 100% before doing anything to it mod-wise. Doesn't idle right? Take care of it NOW.

Also I'd do other maintenance that doesn't necessarily need to be done but would prevent headaches in the end.

New 02 sensor, all new vacuum lines, new plugs, have the fuel injectors flowed and balanced (I recommend RC Engineering), new gaskets where possible, inspect the turbo to make sure it is in good shape, new fuel filters.. I would highly recommend cleaning all grounds on the motor and possible adding some new ones between the starter / engine block and frame and other components that may have faulty grounding (make sure that the ground strap on the exhaust is connected - that's the ground for the O2 sensor).

Oh and read the FAQ!