I was able to use this upgrade kit to drill out my existing front wings as well one of my masts. There are definitely some parts of doing this that are tricky. Its one of those things that the first time around wont be perfect, but your second or third go around will turn out great. Due to that, if you're not confident that you can pull it off, then just buy an a+ setup ready to go.
The tricky part for both the mast or wings is when you start with the pilot hole, then from there jump to the 6.5mm bit, then up to the 8.5m bit. When you keep jumping up in size its easy to accidentally have the next hole not perfectly centered. If you do both of the bigger ones slightly off center then its easy for it to be off. Good news is that its easily correctable once you do the countersink cone bit. With some sideways pressure on the bit you can walk the hole back onto center. Best way to make this go smoother is put the wing back on the fuselage or the fuselage back into the mast each time before you step up to the next drill bit size to see if your on center, then you can correct as you go. At the very least, check for center before you start with the cone bit.
Once finished, I took some wet/dry sand paper to it starting with 400 then 1000 then 2000 grit and it came out looking like it was done at the factory.
Take your time and don't mess it up!
