OBD and tint should not be a problem.but not leather seat. advisable not to change seat as existing seat is design to protect driver during an accident.

so if u change seat , i think things relate to airbag etc is no more warranty . ur side airbag in ur existing seat is wasted , as it cannot put inside ur leather seat if not mistaken...

I'm sorry I cant really help as I havent got my car and I booked e spec only.. haha

if ur parents pay for it , dont need to waste ur time la... unless ur paying for ur car. elder will never understand wat is VSA n airbag, they will keep telling u to drive safely will do . nowadays most driver drive recklessly , hit red light is like drinking water . a lot incompetent driver on the road as well