The signum is souped-up to the maximum safe limit already. If there was more power to be had with the existing set up, GM would have done it.
That statement couldn't be further form the truth
Signum (and elite spec Vectra) is 230 or 250bhp, the latter VXR Vectra is 280bhp, GM did up the power with the existing set up - its the middle management image of the Signum that meant there was never a VXR 'souped up' version, no mechanical reason
.....No end of problems.....
The eml light and limp mode at the most inappropriate times were never far away. Returned the car to 250 BHP /258 lb ft torque stock. No problems since.
Which did you go for?
I've had a Bluefin on mine for close on 40k over 2 years now, I had to download the map that was on the car, emailed it over, they sent one back and away we went.
What a remap does highlight is components on their last legs, also the plug gap was changed on the later VXRs to 0.7mm, I changed and re-gapped my plugs and its been fine ever since
Plus it runs a shed load better on higher octane fuel, I use Momentum99, when I have run it on standard BP or Shell and even on Vpower there is a noticeable stutter on hard acceleration on a very rare occasion but for the cost of 99 I'd rather not have the issue