Got the 496s running pretty good and took it out to test yesterday, first time driving a twin engine boat. I have to say, I don't think it likes the props on it. Fresh Bravo 28s and it did, and kept wanting to blow the props out. Low speed cruising, like 30ish it would slowly fall off plane and blow the props out. Not sure if this is just the norm for this boat or not. After driving it up and down the river to make sure everything was good, I did give it some more throttle and ran it up to about 4200 rpm and starting to give it some trim. The most is definitely happier at higher speeds and responds really well to trim and the tabs.

Where did you have trim and tabs set? You will definitely burn more fuel at slower planing speeds than you will when you get it up on the pad some and the boat should feel looser at the speeds where the pad is working. That's kinda the tell they like to run faster

Tabs were all the way down coming off idle to get it up on plane. Once up and the props were biting, I started pulling tabs up little at a time until I felt it on the pad.

It sounds like you are taking your time to learn the 320 - that's a good thing as it's definitely a "drivers boat". Your 28 Bravo props are fine especially for lower speeds. Hydro Q4's work very well on this hull and will be faster at the top end. The hull doesn't like 30 MPH given its higher x-dimension and notch transom! It's normal for the hull to blow out the props for a second or two in the mid-30's when the hull gets on plane and the engines quickly increase their torque - simply pull back for an instant to let them catch. Here's some advice. Determine where your indicator settings are for when the the drives and tabs are neutral (i.e parallel to the hull bottom). With the drives all the way in - you don't need the tabs fully down to plane off - about 3 numbers lower than neutral should work fine. Gradually increase throttles - it's easier on the drives also. Once up on plane incrementally trim up and increase speed to get comfortable and then do a little more. The boat is quite sensitive to the tab positions and you'll be adjustings the tabs more than the trim. I suggest keeping the tabs perhaps ~2 lower than neutral as you learn the boat. Never lift the tabs higher than neutral and put them down to settle the boat as needed in the rough - lower trim won't have the same effect. If the boat porpoises a little around 45 MPH as it's climbing up on the pad - give it some power to settle it. At 50+ MPH you'll feel a slight, rapid vibration as it rides on the pad and the hull frees up. It's a cool sensation feeling the boat lift up and watching the speedo jump up! As I initially said, take your time and make smaller incremental changes to your throttles, trim and tab as you learn. It will reward your patience.

I really appreciate this reply, this confirms what I was feeling and saw was just characteristics of the boat. The pointers and tips are appreciated as well. I think I may try to pick this from the owner over the winter for next year.