Your 4 blade is a little too big . Im running to same boat , with 25 3 blade . It blows out in 4 footers so I tried half way plugging the holes . Wouldnt even try to get up on plane . Anyhow , When going to a 4blade you have to go to a small pitch . I would say a 23 in a thur hub , or 24 in a over the hub .Im hope ing to try one this weekend myself . Ill let you know what I find out .The only advantage That I can find for a four blade is on the great lake . They dont blow out as much . The boat feels like its higher in the water , or on . And the biggie , more bow lift .But keep in mind , pitch = how far the boat is soppose to move with one turn of the prop . So by going to a smaller pitch , you may slow down a little . About 2 or 3 mph. . 5 for a 5 blade .Oh , and I have a friend that runs a 25p. 4 blade ,but he has a 250 . And he has all the holes open .