Not a full build review, cos I've already built mine and didn't take photos along the way, but here are some pics and a little narrative of the changes made / features I've added. First to say it's a great model to build straight out of the packet, but is easily enhanced with a bit of 'kit-bashing' and pre-thought before assembly starts (learnt the hard way!). 

IP Engineering kits are designed with the wider 16mm NG fraternity in mind, who have a standard coupling height of 25mm off rail. As manx have 2ft 3" in real life to contend with (33 / 34mm in scale), I recommend you get the table saw / band saw / hack saw / razor saw / huge Stanley knife out to trim the bottom off the end panels and re-position the headstock overlays (buffer beam) in the correct position. Actually you don't need to do this, but they look better for doing it and then measure up to scale. 

Next, the early kits have the solebars flush with the sides of the vans, whereas of course we rivet-counters know these need to be recessed under the floor. Not a huge problem, but actually quite a challenging cut with the Stanley knife through the 4mm ply side panel. You can't use a saw because you want to keep this off-cut solebar to size and even a razor saw will gobble up too much wood. 

If you plan to replace couplings with Accucraft round-head choppers at the correct height, you need to cut a hole in both the end headstocks and partly into the floor panel to allow clearance for the chopper housing. The housing itself is modified by simply cutting off the mounting wings, so you just have a rectangular box to fix in situ after removing the hook fixing and replacing it with a bolt or screw from underneath (I still used the hook for convenience). I did leave my housings slightly proud of the headstock, then made up a dummy flange from some strip material with nuts/washers to tidy everything up. 

If you're wondering about the chain rust - I made a mistake with the 'blacken-it' solution, Now I have crystals of iron oxide growing on the chains perpetually so need to replace them. Talking of which, do lose the chains in the kit and get yourself some cosmetic jewellery chain sold in places like HobbyCraft and similar stores. It looks well shiny (gold, silver, copper etc.) but is actually just steel plated in a chrome/aluminium compound which burns off very quickly on the gas cooker hob (hint, hold it with pliers, not fingers) and turns it blue/black. It comes in 1 mtr lengths and is perfect 15mm scale IOM for about £3, enough for 10 wagons!

Last change involving cutting relates to side panel detail - the model is based on G19 which was a bit of a one-off built using an old E van chassis. The other contenders G15 to G18 used old coach chassis (a tad longer but who'd notice) and had different side panel framing at the bottom, creating a gap as shown in photo below. A little bit of cut-and-paste with the panel overlay provided in the kit and the bottom hinges to match.

Swap the plasticard roof panel for a nice piece of 0.8mm birch ply, with small trim added beneath the overhang and roof drip rails on top. There's scope to add lots of (dummy) nuts, bolts, washers, rivet heads and plates, plus the missing bottom solebar/headstock fixing brackets. Also different style grab handles for the brake jockeys and door latches.  As I've said elsewhere, it all helps you to develop from kit-builder to kit-basher to scratchbuilder.