some sort of external antenna will increase your reception by 30-40%. Inside the vehicle , your car body blocks much of the rf signal. There are many mag mts, trunk lip mounts, all that would not require a hole in the vehicle. Antennas would run from $20.00 to $150.00, you just experiment around to find what you are happy with. As for what is able to hear, its a never ending game. Sort of like radar detectors. Police try one thing, sortly thereafter scanners update so whatever is scannable. DMR still has not showed up in the mainstream, and of course encryption I guess will never be obtainable. For us, Motorola p25 encryption is an expensive option. DMR has encryption built in and its much more obtainable by the average department.