I checked again and this is still what Mercury is posting as being a Bravo XR. It may be the latest version from them. But still those gears/shafts won’t take that amount of hp for long. Been there done that and have rebuilt those drives many times on a previous boat with only 525 engines. That’s why I moved up to a SSM 6 drive package.

The XR is just the upper, the lower shown is a B3. The XR upper can be installed on the B1, B2 and B3. I had a XR on a B3

Zoom in on it, the sliding dog clutch is engaged in the reverse gear, also, it
has helical gears,bravo’s have straight cut gears

I have a 35 lightning making 775 hp with Vortech super chargers and my bravo drives would not last half of a New York boating season

Yep
Furthermore Bravo 3?
Where's the counter-rotating setup?

Agree, no B3

To the OP....you can spend the 20-30k and upgrade your uppers to IMCO SCX and run XR or SC lowers and be fine....or you can be easy on it and probably have them live for a while. All about how aggressive you are out of the hole and how much you launch the boat. This topic has been debated A LOT over the years if you search around.

Or you can spend probably 100k+ and convert it to 6's and run as much power as your little heart desires....all about how much money you want to spend and how reliable you want it to be.

If I were in your shoes, not knowing your financial situation as it's none of my business but if IMCO's are feasible I would do that and if not I would have a spare XR upper or 2 on hand and get familiar with changing them so at best you'll be down for a few hours and can have the broken one fixed while you're still using the boat.

I'm thinking this is kinda the info you were looking for from your post? Congrats on the boat!