I was at my GM dealer asking some questions about lowering a NNBS and they tried telling me that when lowering more than 4" there has to be a modification with where the fuel tank sits. After all the time ive spent on this forum looking at what it takes to lower a NNBS CCSB i havent heard anything about having to move the gas tank when static lowering with a flip kit in the back. Any info would be great. Thanks