Hi, Recently had to buy a new head for my Fiesta Rs Turbo as other one was cracked. The one i had on it was ported and polished, the car was running 201 bhp at 16psi, beige injectors, piper cam, t3, grs intercooler etc. The head i have just bought is a standard recon one. If i was to put this one on how much power would it lose?? Will it make a big difference?
Does anyone know anyone that ports and polishes heads cheap?

Cheers.