Looks good Matty but I see what you mean about getting a clean edge from the tape.Also, a good brand of masking tape that comes in thin and doesn't creep?
Did you remove while the paint was still wet or wait until it was dry. I think you maybe you just had some bad, most probably cheap cheerful tape. Try another brand but these products are not cheep unfortunately. If you want one of the best go for 3M £££££££

Imagine the yellow stripe on a Black Storm, Mmmmmm making think now

(:-})