how to install a narrow band A/F ratio gauge in 2000 audi A4 1.8T
 

Do i need to install another 02 sensor? Im looking at autometer #3675 and it says Will work with most factory narrow-band O2 sensors. May require model 2244 in the Accessories. I know my A4's 02 sensor has four wires. I wanna install it so I can see how its running. I currently have a vacuum leak so im suspicious that some power is being lost maybe running to lean. The vacuum leak is causing for the blow off valve to not activate plus I think im running lean cause i can only top out at 100mph and it used to go 140mph. I also wanna get it reflashed to refresh the computer tune.