get the big nuts. I have 1.325 Megabits on my 136 - 1.25 and ran that all last year in not the best of snow conditions and I do not have one bent stud. When I had the same sled the previous year as a 121 - 1.25, and regular nuts, I had several bent and broken studs. The studs on my 121 were Golddiggers.
Just my experience. I did go with colored aluminum backers.
I think they are worth the extra price. I have 1.325 on my Switchback also with the big nuts. Just have not had an opportunity to ride it yet.
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