Hi,
this is my first time here and i’m buying 640i 2013 grancoupe, wanna to know what stuff do i need for it to get 500hp and is mhd or jb4 is better and apart from this can i use custom tune and mhd or jb4 at same time and how much the hp will be? Is worth it having both? Jb4 or mhd for more burbles. I live in New Zealand and i don’t where to buy stuff this car( diffuser, side skirts ,spoiler and front lip).
thanks