I agree.
If you want to improve performance, you'll want a purpose built VHF antenna mounted outside your home and up as high and in the clear as you can safely get it.
You'll need decent coaxial cable. The size/type will depend on how long the run is, how much performance you are willing to sacrifice, and what your budget is.
You'll also want one of these:
https://www.amazon.com/Icom-Antenna-Connector-Adapter-AD98FSC/dp/B00FDWJ0HY
However, you do not want to connect heavy coaxial cable directly to the radio/antenna adapter. The antenna adapter above is designed for testing in a shop, not for long term use. Heavy coax will put a lot of strain on the adapter and antenna connector and can damage them. Using a smaller cable to act as a jumper between the radio and heavier coaxial cable is a really good idea.
And, as I'm sure you are aware, if the agencies did switch to encrypted traffic, none of this is going to work. If you are going to use it to listen to non-encrypted traffic, then it will improve performance over the stock flexible antenna inside your home.
