The VTC6 has a 19A CDR according to Moochs charts. If you have no concern regarding authenticity then they are perfectly good cells to use in your Alien mod, however, due to the low cutoff of the Alien(2.9V from my understanding), I would not recommend running them above 100W. That said, if you pull your batteries before the cutoff then you can go a bit higher but I still wouldnt suggest any higher than 120W with 19A cells.