Difficult to know for sure...guys used to upgrade turbos using their stock turbo shells so the part number may not mean they are stock, especially if you have appropriate boost and hp numbers...you are not very likely to find many 996tt turbos that haven't been modified in some way...even a simple Ecu flash can increase performance...only issue would be adding significant hp without upgrading internals (pistons, rods and crank)...if the seller is a gentleman of repute be cautious of being accusatory as the turbos may have been upgraded and still have the stock part numbers