I have Civic Exi manual 170k driven, I am not sure about Vti but exi have got a tiing belt and it need to be replaced at 80k otherwise if it gets broken you need to overhual your engine cost too much. So i will advise you to get it checked from Honda 3S with good repute and confirm whether vti has timing belt or not.
I did my car tuning a month ago and now its giving 13-13.5 km/l in city without AC my daily drive is around 40kms with 70-80km/h half of the journey implementing some of the hypermiling techniques.
Tappet adjustment is done in engine tuning including throttle body service and computer check, actually they adjust fuel setting with the help of computer.
I am a regular customer of Honda Pit Stop 2S Johar Town Lahore for last ten years and I am very happy with their services and guidence.