17. We noticed that the JBA Y-pipe had two bungs welded in the tops of the pipe for a pair of 02 sensors, which are for the later 4.0s. We drilled a hole down by the collector, like our stocker, and welded in a bung we got at the local muffler shop. Then we plugged the two upper holes - Easy fix. The Y-pipe bolted up to the headers and to the stock catalytic converter without a hitch.