Boat is an old riveted Alumacraft 1544 jon. Very light and simple. Transom needed some reinforcement before mounting the motor.

Motor is a brand new Copperhead 23hp from Illowa Marine (very helpful staff). The 23 runs OK but not perfect, it stumbles a bit and dies every now and then after coming off of full throttle but thats nothing new for a 23. It's also a lot harder to keep the trim in the right place compared to the 12hp and I feel like I'm always trying to adjust it.

Me (210) gas, not much else: 27-28, sometimes 29 in 4-5'
2 people (450 lbs), gas etc: 25-26

Also had a Copperhead 12hp LCT on the boat before this, ran 21mph with 1 person and about 18-19 with 2 people. I almost liked this setup better as it was lighter and the motor ran better than the Vanguard. Just easier to manipulate through channels, just couldn't carry a hunting load real well. Here's a video of the 12hp.

http://youtu.be/tICV-Khm7Y0

This is funny bc i have an old 1442 alumacragt flatbottum and see almost the exact same numbers Except my 12hp lct ran a lil faster at first. My 23 also bogs on takeoff at times and spudders or whatever in the 3400-3650 rpm range. Hauls arse though. My transom angle is a little off tho bc at my fastest speed empty (29), the nose is plowing even with every ounce of movable weight in the back. When i trim it up it planes out better but there is so little prop in the water that im only getting 23-24mph.

Open up the air box on the 23 helps with the stumbling and dying. You can also cut the limiter tab on the idle mixture screws and tune it pretty good to fix some of the negatives with the stock carb.
Take the green prefilter off the stock air filter or get a K&N e4665. any local auto place either has them or can bring them in within a few days.

What do yo mean with opening the airbox?

The air box on a stock motor has a large metal plate under the air cleaner cover. It doesnt allow air to enter the engine without resistance causing negative effects on engine performance. I modified my air box to get rid of this plate. There is also an adapter you can get to run a cone style filter and get rid of the air box all together.

With these airbox mods is it necessary to rejet? Exhaust would stay stock.

no rejetting I did gut my exhaust along with this. stock carb.

Good info. Thanks Puddler