Here is the rule, and I read it the same way.
Turbocharger: The vehicle is limited to a single turbocharger; the inducer bore on the compressor housing may be 2.6”. The inlet will be measured using a 2.65-inch plug or internal calipers. 2.6 bore must be carried 3/4” and must be within ¼” of the wheel. A stock map width enhancement (MWE) groove is allowed. No MWE groove will be allowed that has a width greater than 1/4 inch. All provisions allowing air to the wheel other than via the bore and the MWE groove are prohibited. 6.4 liter Powerstroke engines may utilize the factory twin-turbo configuration.