I just had the same problem, my friend. What I did was wad up some paper towel, dip it in water then dip it in some Orange. I basically orange washed heavily in the back then lightened up as I got towards the front. The reason for wadding up the paper is so you could actually direct the paint ONLY on the stripe and not on the rest of the helmet. I then took some Brunswick green and did the same thing to bring it down a notch. presto !
gm