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 am thinking to get a used waja which already transplant into 4G93T turbo engine, just which to get advice from sifu here, what I need to check is buying a turbo car? and, it 4G93T spare part hard to get?