Well depending on how well you've prepped them, even if you do remove the paint they'll still be scotched/sanded underneath so they'll probably look crap and you'll have to re-paint them anyway. Depending on how bad the paint job is, I would personally just sand out the imperfections with some 1200 grit wetordry paper, using it wet, then you can start to re-paint them properly. As for not wanting to sand away the lettering, you should be fine sanding with 1200 grit or finer.
If you can't be arsed with that you could use some thinners on a rag or brush carefully to remove the paint, I did this to some wheel diamonds someone had primed before I got them, though it could end up melting the plastic.