Some drilling and tapping is necessary to install the optional pyrometer thermocouple into the driver-side exhaust manifold. It's accessible from underneath. Drill a 5/16-inch hole and tap it with a 11/48 NPT tapered pipe tap. Avoid getting metal chips into the manifold because they could harm the turbo. If you start with a cold engine, you can drill most of the way through, then start the engine to drill the last bit. This will blow the chips out as you punch through. Use grease in the tap recesses to catch the tapping chips. Route the lead up to the module and connect it.