I've noticed that climbing steep hills, I can hear what sounds like excess pressure being dumped every few seconds, if on full throttle. Now I imagined this was normal, cos it seemed to match the description of HDi 110 boost regulation. On further delving, it seems this function is peformed by the DW12's variable geometry turbo, which is adjusted under ecu control to regulate boost pressure.
Maybe I've just got a leak, but as it's only apparent at full oomph, I can't think of an easy way to check.
Ideas?