Depends how your going about doing it, if you go to an RR, and have it checked, they will insert the sensor in the tailpipe of the exhaust.. If you have a wideband, that you will have in the car permantly, you dont want to be using the lambda sensor hole anyway, as its too close to the turbo down stream. You will need another bung welded on, further down the exhaust, i think the ideal is soemthing like 24" from the turbo downstream, this is to prevent sensor damage. The autobahn one does only have one bung, as the cat temp sensor (bottom one) isnt needed when installing a decat