if you're not particular about noise and good hp gain, practically you can go to any exhaust shop. i think whole setup may cost you about RM 400 to 500. As compared to famous exhaust shops that may cost you RM500 just for a header.
i just changed my car batt into the maintainance-free type 13 plates 70
before this i was using the normal car battery 13 plates 70
i noticed that the rpm drops more when i on my air cond after i changed my batt...