hi guys,
I just found this tuner in Germany who specialised in Opel tuning.
they produce a little pocket device you plug into the OBD port and it overwrites the ECU.
stage 1 gives you kW 229 / 312 PS, 439 Nm
price 959 Euro
the interesting part is that it can also be tuned back to standard just like this.
you get updates for it via internet and they also provide you with original updates from your manufacture.
2 year warranty
Lexmaul GmbH Opel Tuning Online Shop
so far I can only find a partner in UK , but it might be an idea for any of the dealer here to get in contact with them.
as it's obviously a product from Germany it also has to comply with the TuV in germany so quality is not a problem.