Thanks, Al (I assume), for your questions. Most of the modifications I've done would not, think, be considered common. I'm sure nothing I've done would affect the structural integrity of the boat. Many of the changes affect the efficiency, which is measurably higher than original. I've had brokers take a look, but would they have the same reaction as a surveyor? I think so, but maybe not. Some changes seem to be viewed without a reaction, some are viewed as "really good" and some seem to be viewed with polite skepticism. The bow thruster ports have been faired in with a bit of a flare ahead of the port. I think this is a significant improvement in drag and nobody that isn't looking for it would even notice. Certainly not negative. The next big change was to add a "cuff" to the rudder. This is a stainless sleeve that converts it from a flat slab to an airfoil (hydrofoil?) shape. This gives measurably more efficiency as well as a noticeable improvement in low speed turning capability. Big project, but worth it. The hull just forward of the propeller was faired in with a lot of glass-filled bondo. This must have helped, but I don't know how much. Finally, the hull was cleaned and the bottom protected with two coats of epoxy and then 2 coats of VC-17 bottom paint, usually used for sailboats. The bottom is noticeably smoother that others. The net result of these mods is perhaps as much as .5 knots more speed with a slight reduction in fuel flow. My long-range cruise speed is 7.9kts with a fuel flow of 1.8GPH. I am very satisfied with these modifications and I think they will only add to the market value.
The most significant other changes involve the electrical system. It previously was modified to include a large 4-battery house pack that was only connected to an added 2,000 Watt inverter. I added a wire to this to connect it to the #1 terminal of the main selector switch. The original #1 battery is disconnected. The #2 battery is now also connected directly to the engine control panel. A combiner connects the batteries when either is being charged. Operationally, it is much simpler. The engine operation is just like a car - turn the key and start it. It runs without any manipulation of any switches. So for cruising I just leave the master switch in the #1 position. Works great. A surveyor might look askance at this, as there is no way to disconnect the #2 battery from the engine, thruster or windlass (although each has a breaker or fuse). If a buyer wants it done the old fashioned way It is easy to revert the wiring to the way it was. Another mod was to eliminate the run solenoid. The Cummins engine with the CAV pump normally has a solenoid valve that is activated while running. A failure of this valve or anything electrical will stop the engine and prevent it from starting. Not good. I removed the solenoid and added a stop cable. You pull a knob to stop the engine, and then engine will continue to run as long as it has fuel. The parts are there to convert it back. Then there are lots of mods with little things like cabinet latches, curtains, etc. And now I can't think of anything to improve.