As you have an uprated clutch and a standard gearbox, a little bit of mechanical sympathy is needed. Hold the revs at about 5000rpm and try to slip the clutch slightly whilst pulling away. The clutch will be ok and should help keep the gearbox happier for longer ( I learnt this only after my 4th 5 speed was fitted! Now running 6 speed box[][H])
As for what mod next, I would advise that as you have an exhaust, filter and fmic already fitted, get an uprated fuel pump, an uprated fuel pressure regulator and some sort of ecu remap ( either using your ecu or fitting an aftermarket one)
Hope this is of help to you.
Nathan