A few years back I elected to have a 4 blade MT prop placed on my 2009 SR22T as I was under the impression that I would gain more speed and possibly run quieter. Within 5 years I had to have a blade replaced due to de-lamination and again a 2nd blade replaced a couple years after the first. NO real speed advantage but it did run very slightly quieter ( little change which was more pitch than anything). The plane now has a new Hartzell 3 blade original prop back on it. My advice is to stay with your Hartzell 3 blade.