There are two Hydrmotives. The P5 and the P5X. The P5 is 15.5" and the X is 15". The Maximus is 15 5/8". The Maximus will have more stern lift than the P5X and slightly less than the P5.
The Maximus is our favorite 5 blade for doing modifications and Labbing. The P5X is the least expensive to get into 5 blade technology.
Call us with questions.
Brett