I mow 3 acres with a 54" Raptor SD that I bought used from the previous owner of our house about 3 years ago. My discharge used to clog while mowing and between mowing large clumps of grass would drop on my garage floor. Cleaning the deck was a messy and smelly job so I asked the dealer about those wash-out ports you hook a hose to, but he said not to worry about it, when customers brought their mowers in for service they were always caked with grass.
Then I started reading about different blades on this forum and someone recommended these XHT Hi-Lift blades:
Benefits of the HXT blade are sharper and longer lasting cutting edges. More resistance to bending. We list all the specifications on the part (size, width, length, thickness, etc.) and YOU must know what is needed on YOUR application.
www.ebay.com
I ordered these last season and I won't say they have solved all my problems but my discharge has not clogged or a clump of grass dropped onto my garage floor since I installed those blades. An added plus is these are good people to deal with located in the U.S.A.
Some guys are enlarging the discharge area by cutting, but I haven't had to resort to that after buying the Hi-Lift blades. Good luck and let us know what works best for you.