hello i have 4efte in factory condition .....only air intake  and 2.5inch pipe added with exhaust with 13km/L millage now i have an front mounted inter cooler with me and wanted to swap ct9 with ct12 plz can any 1 help me what else i will be needing for this change.....and what millage effect it willl have as i am new with turbo charged engine...will appreciate if some 1 tell me how to maintain an 4efte and recommend me any good BOVÂÂÂ