Mkc, you need to call around and find a muffler shop that has the bung and find a place to weld it, close to the engine, yet accessible and clearing anything that passes under the vehicle. Seems to me it ideally needs to be a certain angle, I think within 90 degrees of vertical, but you should research that first. Then you need to find a switched source of 12 volts for the heaters. I was told by the meter manufacturer to buy a generic 4 wire Bosch sensor.
2005 Drunken Rav4: 2.4L AWD Limited