Just installed an Enginaire cannister air filter system on our Woods 5182 with a Kohler Magnum 18. Have not been able to find a Donalson for the Magnum series anywhere but saw this company in a MO Green Insustry Directory. The company is based in WI and Bill Decker there is very helpful. The air filter is a cannister type and came with hoses, a turbine precleaner, and a Dust Load Indicator that tells me when to service the filter. It all cost a bit over $100 and I am happy with the unit. He also directed me to the correct Kohler part number for the remote air filter elbow ($30). The Kohler folks told me that clean air is vital for the life of their engines. We looked at a lot of nice mowers at the Lawn Expo using cannister filters manufacturers so I figured this was a good way to go. They can be found at www.enginaire.com. This is a good choice for anyone wanting to upgrade to a cannister type air filter and turbine precleaner.