Why not? Sure it'll void warranty on the suspension if you upgrade it, but it won't void the whole car. Not everyone wants to drive a car that's just like other accord on the road. If I had the money for a new car that I want...330i, I'd put some 19's a mild drop on it in a heartbeat.

I'd say for the coupe: OEM kit if he doesn't already have it, a mild drop, and 18s.