"J" version is named after one of the most famous Cobra owners in history...
They dent the inside of rear fender (nicely) so the seat moves back further, take the seat rails out, move the pedals forward, use taller pedals, move the steering column up, 15" wheel, take some padding out of the seat cushion...and now they're playing with a dropped frame seat that sits even lower and a dropped footbox, and maybe some more forward pedal placement.
Trust me, an inch here...an inch there.
Review some recent threads...an arruminum roller for $39,900.
