All I've got a Toro 48" WB (Proline) with a 15HP Kohler engine and a fixed deck. Problem I'm having is that if the grass is the least bit wet, it doesn't discharge. The deck chokes up and I have to disengage the blades to let the grass fall out. I'm running the blades that came with the mower (4 yrs old) and I keep them sharp. I'm thinking maybe a different blade design or a different pitch of the deck (forward or backward) would help discharge better as it doesn't seem to be a HP problem.