Tried two Chips on my 3.0 MV6, first was a 'Superchip', which seemed to give a slight improvement off the mark and made it feel quite responsive at 70 and upwards and about the same on MPG.
The second Chip, the one I’m trying now is a 'Courtney', which seems to make it slightly sluggish off the mark compared to the Superchip but then does a catch up at Mid to High revs. The Courtney definitely gives an improved MPG, gives around 34 to 38 on a normal run (Manual as well).
I acquired both chips for next to nothing, but I think I would be quite disappointed if I had to pay the full few hundred quid that the Manufactures ask for when comparing their performance increase.
Keep meaning to put the original Vauxhall Chip back in to see if I miss anything, but not too sure how long those alloy lugs on the ECU cover are going to last before breaking off!