I'm just going to be blunt here. To eliminate the factory UTV platform in place for a full tube frame and chassis would be the worst and dumbest thing any race org could ever do.
I think some are confused! No one is saying a Spec chassis where everyone runs the same identical chassis & suspension and only the body work & engine are from a manufacture.
Joey I'm just trying to be objective, how would having a factory replacement lower frame it be the worst thing ever? Honestly I'm really trying to understand how allowing a lower frame that is Identical specifications to the factory frame not a good idea? So if you raced a Can Am it would match a Can Am pivot & engine perfectly. If it was a 2 seat RZR the dimensions would match the RZR perfectly.
The idea is it would be built out of better material (DOM or Chromoly) and would cost less then buying a frame from the dealer. Most of the top UTV builders like the Cognito, the new Jimco & Thad's cars all have less then 25% of the original lower frame left anyways. Even that 25% left is gusseted or plated at the pivot points to make them stronger. You've already butchered the stock frame so much, if the Manufactures were going to get upset, why aren't they now?
Like I asked earlier which got no response. If you bent or tore the front a-arms off the car (Which several cars at the Mint did) and it also bent or tore off the factory pivot points. Could you make your own replacement tabs and weld them in? Or do you need to buy another factory frame and weld that section in?
From these pictures you can see there is not much stock frame left.
Cognito XP1K 4 seat chassis build using stock shock mounts
Thad's FabWerx, I think this was Marc Bernetts or maybe the Speed car?.
Motive's frame rails.
Jimco build
BTW all those Ford TT's in BITD dont have Ford engines. BITD rules allow other engines & Ford does not care. As long as the grill looks like a Ford and runs Ford decals your good to go.