Mower is a John Deere 717 ZTR with the mulch kit. should the pitch be different for mulching? the mower does not provide a very good cut on the first pass (right side seems to be a rough cut with some missed grass)and does not seem to have enough lift to pull up all the grass bent down by the tires. I hope I don't have to get a bigger mower beause of some tight areas I have. I don't remmber what the blade tip speed of this mower is but the new 757 is 18000 vs maybe 16850....will this make a big difference? Any help will be appreciated!