Trooper Wags

Hey guys! I'm new to the world of PC gaming - just built my first computer this past week and installed GTA V and LSPDFR right away and I'm loving it all so far. It's great to see such an awesome community around LSPDFR. My question regards the slots for modded police vehicles. Currently I have a CHP charger and FPIU in the police2 and police3 slots, respectively. The stock, slicktop LSPD that comes with GTA V is still in the "police" slot while sheriff2 is a LSPD modded Tahoe and the sheriff slot is a LSPD FPIS. Now, when I tried to install a slicktop Charger into the Roadcruiser slot, I noticed it drives nowhere close to what the CHP charger does in the police2 slot. So my question: How do I install cars in slots, like the Roadcruiser slot, and update their driving style to match the car. Or do I need to install exclusively in a certain slot to match the modded vehicle? Also, is there any way to expand the slots to more than what comes standard? Thanks guys!