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.
I need a rebuild a RB25 motor. Could you guys lay down which machine shop is ok in dealing in RB engine in things like reboring the liner & porting the head?