Fitting the boost gauge took me about an hour, but the planning took about a fortnight!

I used a TIM 2Bar turbo gauge. My own tests have shown that the turbo produces just over 1Bar of pressure when on full boost, which is just at the point the wastegate kicks in. After asking questions in this forum, and asking Mercedes, nobody could/would tell me where to attach the pressure feed, so I did some research and found an easy place with no drilling or difficulties.

The hardest decision you'll make is where to put the gauge. My facelift car has no really suitable place to fit the 52mm dial, so I decided on an aftermarket pod. Ideally the gauge should be easy to view, but I couldn't bring myself to drill the top of the dash and fit a pod there, so I found a place on the side of the carpeted area of the lower console. It doesn't impede the driver or the seat, but visibility of the dial is a bit of a compromise that I have decided I'm prepared to accept. It also allows me to remove it at a later date without leaving obvious damage.

Photo number 1 shows the tee piece supplied with the gauge, inserted into the black rubber tube which exits the plastic engine housing at the back left corner. The clear tube (supplied with the gauge) is tidied up with cable ties before making its way down to the large grommet which is located under the brake servo.

Photo number 2 shows the inside of the driver's side footwell, with the tube passing through the grommet before making its way to the side of the lower console (some will know this as the transmission tunnel area!).

Photo number 3 shows my gauge mounted in a plastic pod with all bits tidied up and secured out of harm's way. Make sure nothing can get caught or trapped in any of the pedals, and make sure the pipe can't get chaffed or burned !!!

*** Possible problem you may encounter ***
Due to the "pulsed" air pressure at tickover, the gauge needle may vibrate and make a buzzing noise. This will stop above 1000rpm, but is irritating and may not do your gauge a lot of good.

The way around this is to fit a restriction in the air tube, which will damp out the pulses. I like cheap solutions, so I'll share mine. I bought an airflow regulator valve for an aquarium compressor (for about a pound), from a pet shop. This comprises a small plastic adjustable finger turned valve, with two small pipe stubs which fit the gauge air tube. You place this inline with the air tube, then start the engine, and adjust it closed until the needle just stops vibrating. Job done !

Thanks to Graeme for the pictures and text