I've read here that, if possible, it is best to have the booster strap go over the liner's tongue but under the shell. The Cabrio design seems to work quite well with the strap going over the shell tongue, however the top buckle seems to always get in the way. I usually have the top buckle closed but loose and the strap seems to always be getting pinched by the cuff under the buckle. I haved skied with the top buckle undone but the booster strap snug. I guess that is OK.
Today when I took the boots off the dryer, I decided to try running them under the cuff shell, over the spoiler (I think that's what it's called) and over the shell tongue.
It looks like it would work fine but I wanted to make sure it is OK before I melt another hole in the strap (buckle ends up being stopped by the cuff). The straps aren't new and I want to get as much life out of them as possible.
I would have to move the strap because of the buckle being stopped by the cuff.