Vinh, as it says on his website, does modding as a full-time job. It's a good model for high end name brand lights, specially as a reseller w/discounted purchases which he was doing with some brands. He's also gotten good deals on volume buys from retailers, like Illumn.com, and also help from Richard on the driver side, plus he probably has contacts with machine shops, or at least someone that can help in making some custom parts, like copper assemblies, etc.
For modding these mostly higher end lights, he's been blazing the trail because he can afford to buy a $300 light just to see if it's moddable, whether the time put in will be worth the benefit of a mod. So in a way, it's good for all modders to follow him. But it's always been hard to get details from him, unfortunately, and I guess that's still true based on the answer giorgoskok just gotten. That's very common - to get an answer like that, almost as if he didn't understand the question.
Yes, basically, it's mostly common mods but again, he definitely has some specialized skills - for example his tuning of focus for reflector based throwers is outstanding, and because of his profit margins, he can offer "PDT" options, which are hand picked higher performing LED's. Dunno how it works out, but I envision out of 5-10 LED's tested, you can find one that performs a bit better, so he can offer it as a higher cost option, and his customers have no problem paying for it. Also he can crack open almost any light, so he must have a great setup for pressure opening bezels, etc. Think of the # of lights he mods on a yearly basis, makes a very good living at it - that experience alone puts him in a modding category no one else is, or will be, even close to.
So, he caters to the high end buyer, which is a great business model with higher margins. He will also not sell and turn down mods where time/materials is too costly for what he can sell it for. Again, god business practice.
I would just love to be able to see his work setup, the tools, his bench, for example. He can spend some significant money I would think to get what he wants and needs.