yo bro
port n polish the engine head will cost u around few hundred la
the performance u gain is not much la
if u got $$$ then change u exhaust, cam, engine balacing, n buy a stand alone ecu is better
Bro, before doing a PnP, you will have to match the rest of the items first such as
1) Intake manifold porting
2) Exhaust manifold mod
3) Exhaust system upgrade
4) Adjustable cam pulley
5) Cams (optional) if you have the money
Do all these in stages and you will be able to see the difference..
My mechanic can do a pretty good job with very reasonable price!!