Also, not all new B&M Hypers have 7-car trains; the gigas have 8, and Himalayan Eagle Music Roller Coaster, that opened in China in 2019, has 9. I think the number of rows, as well as the train style, is very much a park choice.
Mako and Candy just happened to have 7-car trains because the park chose them. In fairness, I don’t think Thorpe probably needs the capacity of a full 9-car train, so if Thorpe were to build a B&M Hyper, I could see them opting for 7 cars based on the fact that Inferno and Swarm, the park’s existing 2 B&Ms, also have 7 cars. Admittedly, I can’t seem to find any throughput stats for Mako and Candy, but I reckon that even a 7-car B&M Hyper Coaster would be Thorpe’s highest throughput coaster by some distance, especially if it had the typical Merlin baggage hold.
Also, in terms of the Stealth comparison and whether a hyper would undermine it; I think Stealth’s hydraulic launch would still make the ride hold its own against a hyper, as even if a hyper were to be faster than 80mph, a launch going from 0-80mph in 1.8 seconds is a totally different experience from anything that a hyper would offer.
One thing worth noting about whether a Thorpe hyper could hit 80mph is that I think the 4-across trains would possibly require less drop height to exceed it, especially with less cars. For reference, Mako hits 73mph with a 200ft drop and Candy hits 76mph with a drop of no more than 210ft. Due to them having less drag, I reckon a 7-car hyper would only need a drop of 220-230ft or so to exceed Stealth’s top speed.
