who does the remaps that get used by forum members?
I think there are as many preferred re-mappers as there are members of the forum - everyone has their own preference.
I had mine done by Courtenay - but that was because I could and had always wanted to take a Vaux I owned there - no more than that!
Plenty of people will let you know who they use and recommend them!
Good luck!
Matthew
I hope you are happy 
Not a company I would use, just purely looking at their product range shows to me they do not fully understand the car, thus will never get the best from it.
Interesting comment, one of the most respected VX tuning firms about! What about the V6 do you think that they don't understand?
Oh, I don't think they understand injection/management principles, or the laws of physics, rather than specifically the GM V6 lump in particular.
Other than in Chav Power Today type mags, you're the first person to ever say Courtney and Respected in the same sentence

Lets take 2 of their products for the Omega....
Lightened flywheel. What exactly is that going to achieve on a heavy car like the Omega, except more vibration due to the lack of the dual mass?
4bar fuel pressure regulator. It will take the engine manament system fitted to Omega approximately 5s once it goes closed loop that it is overfuelling, thus adjusting short and then long term fuel trims right back to ensure the same amount of fuelling as before. So it will make a difference the first time you use the car after fitting, until it warms up.
Then I could rattle on about their air filters, which on the Omega, common consensus is that 'performance' actually
reduce performance. And so on.