Bergs is the kit that I have. I'm pretty sure I bought it from Wise Sales quite a few years ago. The aluminum caps thread on fairly tight making them feel like something is wrong, but they have not caused any damage to the plastic threads on the generator.
I just looked it up real quick and it looks like these extended run setups are getting pretty expensive these days. I remember only paying $129 for mine and now that price will only get you the caps, hoses and fittings. I still wouldn't bat an eye at the cost of a system that works so well. The extended run tank was the best investment I ever made for my dual Honda generators.
