Extension box/ Mercury ITS

[Wild Card 09]

As I´m putting a HP525EFI into my Outlaw (26 footer, 2150kg), I´m considering fitting an ITS transom at the same time. Extension box, 7" setback and integrated hydraulic steering. Sounds like a good idea (like alot of things do before you try them!)
They (extension boxes) seams to be quite popular on bigger stepped twins.
So what does it do on a unstepped single? Is the X dimension adjustable? Which prop will work best: Bravo, Maximus, Hydromotive? Is the power (to weight) too marginal or the potential speed range too low (75 - 80) to get the benefit of cleaner water further behind the hull? This must however work similar to an outboard bracket.
Anyone with experience of an IMCO ext box or an ITS?
Thanks
Stephen

[Wild Card 09]

I´ve been in touch with Mercury racing and they say they´ve run this settup on a 25 outlaw and a 27 Fountain it runs good. They said I should maybe raise the X dimension a tad, though. I shall find out more in Miami.