If you have replaced any part of the turbo control system, you will have probably disconnected the vacuum/boost pipes. However, it is not easy to remember which pipe goes where. The following shows the correct arrangement of pipes, taken from a totally unmodified car. This is applicable to fortwo 450s and Roadsters only.

Note - if you have a fortwo 450 Pure, you won't have a cycle valve and therefore you will have a 'bung' over the centre port of the wastegate actuator.

Wastegate Actuator:

The whole arrangement (click to make bigger):