Nato, are you using the TX capabilities as well? If so, I know little to nothing about that, but I was looking at the Hypario dual band antenna mobile mag mount on amazon for $12. For the unit itself, there's a lot of comparison links and counterfeit warnings for the Nagoya antennas. I'm waiting for an adapter for my BNC to SMA female so I can test the RX with an RR homebrew OCFD attic mounted anttena.
Homebrewed Off-Center Fed Dipole - The RadioReference Wiki.
Right now, my two UV-5Rs have two different stock antennas. I don't know their model numbers, but one is taller and RXs better than the shorter one indoors. I will say this, I'm able to receive indoors on some frequencies that my other traditional handheld scanners will not. I have no idea why to be honest.
Also, there's a car cigarette receptacle power feed that's available that I was looking into, but the reviews mentioned something about it getting extremely hot on TX mode.
Hope it helps.
edit--welcome to RR