Does the loose bushing kit bring the wb in a little bit more because the bushings are lower? Also does it make the turn better or just quicker?
The bottom bushing is still the same so wheelbase is not changed.
Adding any softer bushing or lower top means that they turn so much more than with stock bushings, but still not quite as small a circle as Indy or Ace when I tried them the other day, after putting on thin risers with small wheels, so I could get the absolute most out of the turn, down to about a 4m circle which is crazy to think how tight a turn that is. Without the riser and normal sized wheels, I got wheelbite first on the low tops / looser trucks, so there is that to think about too.
If you want a lot more turn and can deal with how much the trucks move, they are good, but if you might struggle with loosey goosey wheelbite, then tightening them down more will work - just watch the kingpin clearance / catch.
Note: I still don't have access to the green bushings here in Australia, but I usually cut down stock bushings, which are the same duro and end up about the same height. Even just using wax on the pivot point and on the bushing contact sides will make your trucks feel so much more loose with the same stock bushings in them. Tried that too, just to see and was very surprised how much more they turned.