I was chatting to a workmate who up until a few months ago was working at Vauxhall and still has contacts there.
Subject came around to the new MK5 Turbo (as you do ). He's been told by one of his ex-colleagues that they're having real problems with the build of the MK5 (all models, not just the SRi) at the moment.
Apparently, due to manufacturing quality problems a lot of the Astra's are suffering with leaks into the cabin area when it rains hard. Pre-production models were OK, as they were practically hand-built and checked and rechecked, but the production ones are being a bit of a headache.
The advice I got was, if you want one, hang fire for a few months until the situation stabilises and they clear out the ones which have had to be reworked etc.