Best upgrade pound for pound (ive got the same car as you) will be an m50 inlet manifold conversion and big bore throttle bodies.costs about 500 quid to do and will give you 325 power :) Theres a guy in Chelmsford that does it,goes by the name of Alpina527,ive got all details when your ready :) I def getting mine done...soon as Ive sorted a few other bits 1st ;)