Which Hull are we talking about here I wonder? I have the modified v 2004 2520 xl, 225 and my numbers are spot on with Hotpursuit's numbers. That's trimmed with no tabs, but sometimes depending on fuel load and wind I can bang out another .5 with my tabs set right.
I gotta say, I do my own bottom work and many other boats every season and I've seen some jacked up paint jobs that easily rob 5mph from a boat. That's testimony from people I've done the work for too! Think "baby's ass" smooth or else your paying in performance. This could also be an engine problem as well, an injector usually doesn't just clog, they get restricted first. Hope this helps a bit, good luck!!