Never have, but have seen it done on old time drag cars. They usually didn't take the extra step of welding in tubes though. I guess a lot would depend on how much you removed. Obviously, the bigger the hole the more you weaken the frame. What you are sacrificing is "beam strength" which is the resistance of the frame to bend under downward loading. It is hard to tell at what point you make it too weak.

Best advice is not to do it, but that is based more on erring of the side of safety than any proof I have. The welded in tubes certainly are better than just cutting holes, which would also allow water to enter the frame. I agree it would lend a racey look to the car, though.

Maybe one of our engineer types, like Brian will have more accurate data.


Don