I have a 28 Eliminator Daytona TD. After trying to measure properly it appears both propshafts are about 1" above the lowest point of the outside sponsons.

Would extension boxes improve performance on this particular set up? Or, what would be the ideal set up on this particular boat for maximum performance? Is 1" above the bottom a pretty high x-dimension? Any suggestions would be welcomed...

Cats generally can run very high X dimensions. The bow is carried by the cats lift. On my last couple, I was running SSMs about 3/4" above the bottom (directly in front of the drive).
I've only seen a comparison with, w/o Boxes on a couple Chris Cats, and they didn't gain much speed. Not sure about your application.

On older 28' TD with boxes and Bravo 1s, about 1" up from the bottom, measured right in front of the drives is all you want. Any higher than that will be tough to get on plane. At 1" up and 36" props, it is real tough to get on plane without using the tab. It easier to get on plane with smaller props.

You need to measure from right in front of the drive.

what about a 26 single with the i.t.s?

1" above the bottom is what Eliminator recommends on 28 TD, I called them and spoke to their head rigger last spring. If you put a box on remember it will lower X abot 1" so you'll have to make that up with shorty drive... What I like about boxes is its free length to the boat (improves ride quality), planing is much easier, and the water is cleaner heading to the props which can reduce slip.

The extension box will help dramatically with planing. It will also help slightly when in rough water. I had a box on my 26' cat and could plane easily with the prop 2" above the pod. The boat also planed with true cleaver, although it did spin up before grabbing. When the boat was loaded with a handfull of people, the box actually caused the prop to hook too well and it bogged the engine. This could be a bad thing if you use too much throttle. You'll end up twisting off a prop shaft or vertical shaft.

that is the problem I'm having. It bogs down when loaded. I thought maybe I was too deep in the water. will a 2"shortie help?

Eliminator has been fooling around with the 28 and by raising the drives up 1 or 2 inches the boat gains 5-10mph top end. The downside of course is the added difficulty getting the boat on plane. Powerboat just tested a 28 with 525's and the boat ran 120.4 but the drives were mounted higher than normal. In 2001 they tested a 28LP (open bow) with Teague 620's and it only ran 114.5. Raising the drives on a 28 works but you sacrifice planing ability.

Hey Paul how are ya? I spoke with you on the phone before about the Hydromotive P5X's. When you mentioned Eliminator raising the drives on the 28 by 1 or 2 inches is that with or with out boxes? I would think that the P5X's would be a big help with planing after raising the drives. They were a night and day diff vs. Bravo I's getting on plane. As I stated, my drives are up 1 inch from bottom, what are your thoughts on going up another inch without boxes? Are the boxes a waste of time on the 28 TD's? Have a good one...

I think boxes make it easier to get on plane but I don't think they give you any speed, at least not on a 28 Daytona. Did you end up getting P5X's?

If you go up an inch on the drives you should be about 5 mph faster.