Thankyou all for your input and the votes.

I've gone for dark red, getting a sample of the stripe sent out by a graphics company to see if I like it. Otherwise I'll get a custom colour stripe made up.

I realise this isn't going to be liked by everyone but I've always done subtle modifying and I want to do something that sticks out and is just very different (never seen this done on a MK6 Fiesta) for a change!