A little back story; I hit a submerged object last fall and trashed my drive and transom assy. over the winter I freshened the engine, replaced the transom assy with a new HP unit and installed a brand new take off XR drive that I bought from Outerlimits. The engine makes 25 more dyno confirmed HP than it did last year, buy my boat is about 6mph slower than it was. The only real change is from going from the sweptback XR to the older style XR. Both are 1.5 ratio. Any help would be appreciated.

Still turning the same 28p Bravo 1 prop about the same rpm

I think they run exactly the same.

Is the new XR low water pick-up? Your 100% sure the ratio is 1:50? I bought a brand new drive last year and was told it was 1:50 and it was LWP, my drives were DWP. So I had a port LWP and a Starboard DWP. Took the boat out and it listed and RPM was off by 400, turns out wrong gear ratio in the new drive although case said 1:50. Switched the lower case to DWP and correct gear, issue solved. It was probably more the gear than the case difference.

The tag is stamped 1.50 and I am still running 5200rpm at WOT. But no, I am not positive. New drive is dual pickup, just like the original

Your RPM's would be down if it was the gear ratio so count that out. You say still running the same prop but did it have to be repaired or did emerge unscathed?

When you freshened the engine, what got changed? Hp is 25 more, but how does the torque compare?

Yes, same prop. It was not damaged. The engine just got bored .030 and a new set of pistons. Same heads and cam. Cam degreed in the same. I doubt the torque curve changed much.

The swept back XR's use the same gears as the earlier square like cases. There shouldn't be a speed difference there. However, if your original sweptback drive had helical gears (non-xr) it would have been faster. XR straight cut gears take more power to turn.

The original was an XR as well. I was just thinking the lowers may be more streamlined on the sweptbacks or something of that nature.

6mph is alot. Either the engine isn't making the power it was or that prop is NOT in the same condition.