If you are going to allow a 4 bolt in, why not make it easy and say ANY three bolt allowed. Then you only have to regulate the new 4 bolt stuff instead of watching after every turbo? There is no three bolt turbo that on paper has more potential power then the new 68/70. 67 three bolt weight break. Anything else no weight break. 4 bolt maybe weight penalty if it proves to be too fast. Why make rules that are really hard to enforce and will probably never be challenged and if challenged nobody will know how to check????