I run an old Woods Vac with a 72" deck. I've found that the hose size and tank exhaust baffle restrictions were limiting factors. So, bigger diameter hose, high lift blades, and an altered baffle to let more air out took care of all my problems with it. You might RAISE up the deck because air inlet is starved, so suction but no flow. It's a balance. Also, my original hose wore out/deteriorated, bought a new clear one from Amazon. It has a smooth inner liner, not rippled. Grass, leaves, twigs, and a brick once, now go by so quickly that I believe the airflow situation once it 'leaves' the deck is very important.