Stefan,
First of all I know how you feel about your Cobra projects nearing an end. My has already dwindled, however, I still have those AMP rear A-Arms to install - I'm procrastinating. I don't have personal experience but would think .82 overdrive would be what you want - anything more may be too drastic.
Just curious - where do you live in Spain? You can reply offline or direct if you would like. I've heard of fender guards - in fact I use one but to use an American Flag - I would of thought you lived in France!