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 recall theres some way to by-pass the OEM temperature map for airtrek ECU to start the fans, but seems like the old forum had gone so sifus please help me with this.