yes port and polish done correctly will definitely improve performance...
price depending on who is doing it... there is no fixed price for port and polish job...
u can try nastyportflow in usj 1, behind summit.... they have some high precision tools there.... its not like u can try n error when it cmoes to pnp ur car.....
If you in jb can try xh racing,call0197853245.
I did my 6a12 v6 pnp together with 3angle and skim head at xh racing ,jb.price affordable.definately increase hp but need to adjust valve timing.
Evo 7 Few unit Rallyart ECU for sale direct bought in from Japan RM 3000
Increase 10-50 H/P from stock engine, 270++ km/h
Open speed cut, very good response, RPM Rev...
Engine specs here, as they come from the factory. Also additional useful info like how much boost the engine can hold on standard internals, and other mod potential.