Everything said thus far is true. I learned to drive an Allison on an XB2003 and the side steer and the weight of the boat (first with a 225 promax, then a 280) plus that console "air dam" were definitely limiting factors. Since then, I've owned or own many different models. Amongst the current five is a 1995 GSE with a 200XS SS (2006 motor) which will do top end of 85-87 routinely despite load. However, one day and one day only my son brought her back with a 94.3 on the gps--light load and a tailwind, so that number is definitely an outlier.
The XB2003/280SS I could get high 90's routinely, but the fastest she ever went was 101 and change. No matter what prop, or setup change there simply wasn't any more there. Mine was a 1998 and I swear it was heavier than any other xb2003 I've driven. Felt like it had a lead layup coat. But the limiting factor on these boats (XB2003) in my experience is that console, followed by hull design/frontal area.
Years ago, I posted a thread on "what's the fastest anyone has had an xb2003?" The winner at that time was Myron who reported a high end of 107. Now on that boat, that's really hanging it out there. Personally I'd never want nor have any desire to run an xb2003 that fast. IMHO that's a 100mph hull before the spook factor shows up and over 101, side steer, you can see the angel of death or at least his cousin angel of hook in the backseat from the rear view. Having said that, the hull is sluggish enough to give you a slow motion warning (compared to an XR or SS) that makes a reaction possible. Everything happens a bit slower in both the XB2003 and XS2003 in terms of the hull saying, "I'm looking for a place to spit you out" whereas the XR2001 and especially the SS says "I'm looki....(WHAmO!)
My current XS2003 GSE with the 200XS has become a favorite go-to boat because of several factors. The 200xs SS is so quiet and so good on fuel economy, you'd think the gas gauge is busted. It has a Stainless marine gauges for both trim and hydraulic jack plate height, which have marks telling me where they are at all the time. It has a wide angle ski-type rear view mirror so I can see the height of its rooster tail and I sometimes use this to gauge whether or not she would like more trim; rule of thumb so I've heard is that you are losing bite, lift, and efficiency when the heighth of the rooster tail exceeds the top of the cowling on top end. She definite gives you plenty of warning and even repeats herself as she gracefully announces "I'm fixin to do something stupid!" Whilst beginning to feel as if on ball bearings and starting a starboard lean. Sometimes I'll throw my left leg over more to port and lean left with rest of me and she will get over it. I've never (knock on wood) swapped ends with this boat. It's just too forgiving, and announces her intention so clearly that anyone with experience will see like a flashing neon sign.
I think I'll add a side-slide seat to the GSE. That might gain me a mph or two on top when solo.
It currently has a Detwiler hydraulic jack plate with 11.25" of setback. Great unit it is. The steering on this boat is also hydraulic, my only Allison to have it, and though it makes for an easy drive I'm just a dinosaur and prefer the ride guide because of the tactile feedback and mostly the steering wheel rocker trim switches.
Personally I'd never have turn signal trims on an XR or SS. Simply for me, not enough cushion in reaction time. These hulls do EVERYTHING faster, and you gotta keep your attention wired tight. My personal best is 117mph on an XR2001 / 300 drag turning a 24 Yamaha at Lord knows what rpm, prop worked by Jeff Calbaugh and this prop is or was owned by Bryan Welch.
Todd Bucknell's XS2003 to me was a benchmark for what this model is capable of. Will never forget the sight that fully loade "bThtub) fully out of the water at 106 with a load of victims ..um ..passengers in her. That setup was DIALED.
Lastly, I have found, running a stock sport master, that my highest top end numbers on the GSE are always with the gear case set LOWER in the water, NOT higher. She loves like 3/4" to 1" below the pad. You can watch the gps lose mph as you raise up the height from there, regardless of prop. I think it's because of the subwoofer and amp up in the bow.
Sorry for the long post. Was just in the mood....Be safe.
Lou