I made my cold pipe hole the same way. I didn’t find a good piece of rubber for the hole. I found the battery fit well and I made a hold down bracket with holed bracket material from home depot. I’d appreciate a pic of the fender area. jhtopilko@shaw.ca
The biggest difference I noticed with and without the HID lights is the fact that the HIDs will positively light everything up and you’ll have to re-aim your lights.
The older style reflectors and lenses had more mini-lenses breaking up the beam and pretty much scattering the light every which way.
Take a look at a modern headlight assembly compared to an older style one. You’ll notice that the newer ones have a clear len as the reflector technology has made huge improvments over the older style headlight lenses with many facets.
That is why when you drop an HID system into an older car, be prepared for every nukka to be flashing their highs at you because the old style headlight lenses will scatter the HID light EVERYWHERE.
Other than that, I think they are cool.