from what I understand, are you saying...
these guys duplicated a mild steel chassis and built it in cm and are using the cm chassis?
they are running a lighter car (chassis) therefore winning a lot ?(cheating)
If that is the case, are the ms chassis required to be a certain thickness in material, say .120?
If so, all you need to do is get one of the nhra inspectors to come in with their sonic checker and inspect the thicness of all the tubes in the chassis.
If the tubes check out thinner, say .083 or .065, then it would be either thin wall mild steel, which would be illegal, or cm, which would be illegal, and you would need to bounce them out of the running.
If it is .120 , or whatever is requiered it could be ms or cm, in which case, I do not see any advantage in the cm as it all weighs the same.
You will most likely have to pay the inspector to come and check out the chassis, but you could get the other competitiors who are complaining to pony up the bread for this if they are suspecting cheating here.
Then it would be in the other guys court so to speak, if they want to subject the car to the inspection, or save face and not continue with the chassis....if they back out or refuse the inspection, it would tell me they are cheating.
also, these chassis from the red cross are most likely mig welded, if buddies is tig welded, which is kind of required for cm then it could be cm or ms, but it still would not be a chassis bought through the red cross.
I also would question why someone would go through the trouble to duplicate a chassis in the first place, unless there was some way to gain an advantage....
good luck here...
ed