The Whistlers and earlier Unidens are not designed to get P25 Simulcast *it's a cross of the fingers and hope this works* My WS1080 sits here benched and worthless on P25.
I drove from Chicago out into Iowa with 2 scanners and my Unication G5. The old, OLD Pro96 from 2004 blew the WS1080 out of the water, heard far more systems there and back. WS1080 was basically silent and choppy at best. Unication G5 Pager was perfect, crystal clear just sitting in the drink cup holder there and back. I only use it now.
The only thing you can try with those is a directional YAGI antenna. Mobile use of the Whistlers with that design are a total crap-shoot. Every 10 feet it will change.
There are videos on YouTube showing your scanner next to a Unication G4 on the same SITE/SYSTEM. The results are as I said above. Good Luck.