If you haven’t already added the jet foot intake fins, I would recommend it. It made a difference on both the 115merc and 140 Suzuki jets I had on my 18’ Alumaweld. More positive (as positive as a jet gets…lol) steering and 3+MPH top speed.
No point in repeating what the others have said for spare gear. Lot of good suggestions there. It was a bit of extra money I really didn’t want to spend but I’m extremely happy I bought a Honda capstan winch, it never leaves the boat. If you were a raft guide you will transition into jetboating super easy, I grew up canoeing and it really helped with reading rivers. The biggest adjustment, as previously mentioned, is being aggressive. I struggled to get the old “hold and slow down” habit out of my system instead of trusting my channel selection and trusting the boat. You’ll love it when you get it all dialed in.