So I finally got my hands on a 25P Tempest Plus and it made a big difference. I'm getting the lift I was looking for and finally got some speed out this tub. I was running 66 mph turning 5400 rpms with two Big guys, 1/2 tank of gas, and full of gear. 2013 Z9 with 250 Merc. Before I was only hitting 59-60 with no lift with the same setup and less fuel even.