Boost the WJ is a good pump, with the Energizer on there you get rid of the biggest problem with a jacuzzi-the bowl. The impeller is next and they can be made to work real well. My WJ pushed my last boat into the mid 90's first time out with no setup, same as a berk has done in similar boats. No doubt in my mind that the boat would have done 100 with a little tweaking and some cleaner water(super choppy out-couldn't stay in it too long). Unfortunately after the first time out my wife shook her head at me and told me we needed a bigger boat.
Get your impeller detailed by Jack @ MPD and add the shoe & ride plate. A bowl detailing will help to, but I would do that after the shoe-ride plate and impeller. You wouldn't notice any difference with the berk IMO.