If you don't know your boat intimately, make sure you know your boats mph at most every rpm point before you install the shower. Reason why is sometimes the the pick up tube makes the props cavitate. If this happens, trimming back the pick up point will need to happen. Just a heads up.

I sure don't need anything like that going on, having enough trouble now with some of that

I built a simrek style, pretty easy fabrication. It lowered to speed on my BIII application by a few mph. I talked to a knowledgable friend who recommended cutting the tubes so the bottom was just even with the top of the cav plate. Got the mph back, and no difference in water on the drive that i can see on a video.

and with Bravo III it is important to make sure your trim limit is set correctly. 21.75 inches center pin to pin. This is the same measurement for all Bravo outdrives. Alpaha one GEN II is 20.75 inches FYI

Cutting the tubes down sounds like an option, or get the drill type

Agree it's important to have the limit set (21.75 or less) so you don't trim past where the drive has no support laterally. Only time I get even close to the limit is putting the boat in or out of the water.

Proper trim limit for Bravo III its so the outer prop still grabs water instead of air if trimmed to high especially laying the hull over hard in a corner and giving it throttles.

Volvo Penta DP with no trim limited and trimmed too high - I have seen this break away the coupler (the one that saves the drive from prop impact - its there to break away taking the shock load from impact).

Also to high of trim while running & steering is very hard on the U-Joints and the yoke as trim limit plays a role in this as well.

Just to stir the pot not everyone is sold on drive showers. I do not run one. I have never seen actual proof with temperature gauges that they significantly lower oil temperature and I believe that if they were that effective that Mercury would incorporate some kind of built in shower. I have had people report speed losses of 2-3 mph. Without mounting a go-pro back there you can't even be sure it is pumping water at speed. There is a lot of water spray back there and I doubt the upper stays high and dry and as mentioned the pickup can disrupt water flow to the prop. All just my minority opinion and experience!

I've done back to back comparisons on our first boat a 223 Powerquest 454 MPI/Bravo 1 and the next boat 95 Baja 272 454 Carb/Bravo 1. Both boats when I checked the drive after running with a bolt on Simrek the case was much cooler and not white scaled over. Also the drive oil did not go to hell as fast when I had the drive showers on. First hand experience. The boats barely broke 60MPH so didn't notice a speed difference with/without.

Here's a video of an install ( not mine) and running the drive shower, found it on Youtube https://www.youtube.com/watch?v=iPOqoLWLwPg

What's a good source of the Semrek's?