How would a 12 volt battery possibly give you 50 more HP? My BS filter red light is on. The battery's maximum cranking amps which can only be sustained for seconds, is 1275, which equates to 20.5 hp. Of course the 12 volt battery is never used to drive the wheels anyway. Since a regular lead acid battery has at least a third of that pulse cranking amps, the difference is only about 14 hp. The difference in weight will certainly not give you 50 more equivalent hp. I can do that math too for a given acceleration and known vehicle weight and an engine hp rating, if someone wants to defend the 50 hp difference. (F=ma). I can almost do it in my head since you are talking about roughly a 0.7% change in mass, it's not going to be 50 hp. I recognize that no one on this forum is defending those claims, or is inclined to buy this expensive battery. It does make you new FFH owners appreciate your lithium high voltage batteries however, which must be worth $100K by the standards of "Group 34".
I just passed 100K miles on my 5 year old FFH, with no problems other than under $100 nuisance issues like 2 new tire pressure monitor sensors. I've got the cost of that event down to about $60 per tire now. I'm glad I didn't waste money on any of the 100K mileage warranties the dealer was pushing. My average long term FE is 40.3.