[stevenoble]

Adrian, I think that cowl will need to be re-painted. It looks like the red has reacted with the white and has cracked on the second photo. Personally I would sand the whole thing back with wet and dry used wet. Make sure you remove all of the red and sand the white so that it is smooth and blemish free. What brand is the red by the way, it would help to know..?? Once it's all smooth clean it off with warm soapy water and allow it to air dry, then apply a nice even coat of fresh primer. Allow that to dry thoroughly, then wet and dry that back until smooth and re spray the Tamiya TS26 white. Let that harden for a week until you do any masking on it. The tape can mark Tamiya TS very easily if it's not properly hardened. Although it may look dry it can still be soft underneath.
Now the masking. Use Tamiya tape only. Stick the tape onto a cutting mat. Then using a steel ruler and a fresh, sharp, scalpel blade cut the tape into a thin strip, maybe 1mm wide. Use this thin strip to mask the cowl freehand. You will find that the thin tape will follow anywhere you want it to go and will not wrinkle. Once that's done you can use the thicker Tamiya tape to fill in the sections where you don't want any red. I also sometimes use a plastic bag for this taped on so I don't waste loads of expensive tape. Spray the red in light coats at first especially at the tape edge to prevent any paint creeping under the tape. You could also spray some clear first or a little of the white to seal the tape edges and prevent creep. Once you have the red on and it's the correct colour leave it for 30-40 mins and slowly remove the masking, don't go fast or you may pull off the red you just applied.
I hope all that makes good sense because it's a lot to take in. Any problems post here or PM me and I'll try to help you some more..
Oh and one last thing. Did you spray the white on first and then the red, or red first and put the white over the top of the red..?? Looks like you got some pink hue in the white on the second picture, almost as if the red has bled into the white..