If your referring to the Hydrocarbon Trap ?? you need to read over posts 2-4 again..The 05+ has never had an air silencer in the stock airbox..Your thinking of the air silencer that was used in the old 94-04 cars..The only other device found in some 05+ mustangs are called intake pulsation tanks that are attached to the bottom side of the stock rubber intake tube..And again, only some 05's and up have them and were installed only on cars with automatic transmissions..