the gauge will just have 3 wires. one earth, one power, and one that you will need to extend to run through bulk head to the bay. drill and helicoil thread the downpipe, or just drill and weld a nut in, then attatch sensor and your away. as said above it wont be something you can trust unless you have a wideband. but saying that il only be running a £15 ebay sensor till i can afford a bosch wideband sensor