My 2022 Tremor does that right around 80mph as well. I've read it could just be the stock tires it came with since it's an off-road style tire, but I've only had it a month so I can't say if that's the case for sure.
Saying that Granger takes away interest-free financing, while saving at least $1000 (probably a lot more than that), just makes me laugh. The practice is not misleading because when you get the initial quote it says there is an admin fee, and then lists it all out as you continue. Granger...