My 2 cents.
Honda guyz would charge you alot for your audio installation or fog light installation services or even keyless entery (assuming you buy a city)
Plus that system of engine that has been tempered by an electrician/mechanic gets its warranty void. I asked them specifically about this. You install wider tyres, the suspension would not be covered in your claim (if any). You install keyless entry, your central locking warranty (factory fitted) shall be void. You install massive audio system, there goes the alternator scope.
Its not like they would not touch the ECU electronics if you installed an aftermarket audio system. Although both a electronics based, yet completely independent.
Note: you install CNG and your complete engine warranty is void.
Hope you get the picture.