Our Bayliner came with a 14.5 x 19 pitch prop, engine is the 3.0 4-banger, drive ratio is 2:1, and I swapped in my friends 14.25 x 21 pitch prop...

Altitude here is 4400'...

Holeshot seems to be un-affected (nearly instantaneous on-plane time, empty or loaded)

Cruise speed, picked up some speed fer sure, 2800 rpm was about 22 mph, now 24-25. 30 mph used to need about 3600-3700 rpm, now only requires 3400...

Top speed, WAS 42.8 once (by myself) on the GPS at 4900 (a little high there, one reason I wanted to move up a size), and that was with a clean, shiny bottom...Sunday morning by myself I went for a blast, after playing with the trim I got 44 on the speedo (which is real close to accurate) and tach was between 4700/4800, and I still got plenty of calcium deposits on the bottom to clean off!

Haven't towed anything with it other than a stranded boat once, so no clue on that.

But it seems the 21"er did perk it up a bit!

thats very interesting.. i also just got a 18" searay with the 3L. From the dealer it came with a 4 blade alu 19" prop.. on searays site, they suggest a 21". I picked up a 21" 3 blade SS prop for failry cheap a few weeks ago (have yet to test it out), but just got a 19" 3 blade SS of ebay for an okkay price.. have not tested any out.. but cant wait to i get some time to see the differences..

the 21" should fly when by myself.. but am thinking with the miss's and 2 kids, may struggle.. hence why i got the 19" as well..

tsandu, for a 1 mile or so trip from the dock to our anchored houseboat, I had me (200#) my son (240#) his wife (wont say) their 4 kids (6, 4, 3, infant) and my sons 1/2 brother (150#) on board. Boat got up just fine! I'm sure top speed would've been down, but I was way happy with the 21"er for that mile!

Your boat's probably a few hundred# more than ours, but I think you'll like the 21 regardless!