hey guys i have two new 350 mags and alpha drives on my 1988 272. i have 21 pitch props and i'm not getting more than 52mph, could i get some help?

What are the RPM's at WOT ?

i'm running about 4900 rpms

are their vent hole in the props? gps speeds? that boat should have 23 p props on it...

Ours came with 21's cleavers . Put 383's @ 425 hp and 23's and turned them at 5200rpm 69.9 on gps.

Yup my 272 i had i tried 21 Mirage and a 23 Mirage back to back. 59.9999 GPS with the 23's and 39 MPH cruise @3400. I lost 3 MPH with the 21's cruising and 2 MPH on the top side. Only mods were timing locked at 34 MSD coils and K&N flame arrestors. Top end RPMS were 4800

My 89 272 with 420's(came with 365's in it and had problems the second week out) and Bravo's had 23 mirages on it and at 5200 it was running just about 72 mph(in 3 ft seas)..God I miss that boat.