The bottom two can be reached through the wheel arch from underneath using a ring spanner, assuming they are the original nuts and not rusted up. If they are rusty then a strong 1/4" ratchet and 6-sided socket is in order. The top one is best reached from underneath from beside the cat using a very long extension bar and universal joint. There's no room behind the engine to get to it from the top unfortunately because of the SAI rubbish.
Don't forget to disconnect both O2 sensors - one on the bulkhead and one under the plastic cover behind the airbox.
It takes a lot of wiggling, but it will come out. Its worth removing the driveshaft heat shield from the gearbox as that gives a bit more wiggle room iirc. Consider the driver's side gearbox mount may also need to come off - it does on the S8 with the 5HP24, but the 2.8 has the smaller 5HP19 so it might squeeze by.
You'll probably need to get it quite high in the air to get it off so you have room under the car to rotate the pipe. Again, the S8 needs this. Can't remember for the 2.8.
Good luck
