.Mil standard is 10.5"
The dragon's breath will chew up that can quick... Some use Inconel alloys, and that helps, but 7.5" is awfully short.
I personally and professionally recommend a SilencerCo SpecWar K. It is a pretty small can, and designed to be hearing safe within a vehicle.
As for color, you can get DuraHeat from DuraCoat/Lauer Weaponry, and it comes in like 50 colors....
You can also get a cover, and you probably want one if you have ever accidentally grabbed a hot can and left most of your palm behind...