I've never had a baffle in any of my exhausts, and never had a problem with it. My hornet and the fzs 1000 aren't actually too noisy providing you're not ragging it, both of those got through an MOT without the baffle fitted. The ZX9R I had previously had a SPE engineering tri-oval stubby, and that was a fair bit louder - had to put the baffle in to get it through the MOT, but it comes straight back out afterwards and I never had any issues (in either Leicestershire, Kent, or London) with the plod. Think as long as you don't rev the tits off it past a police car or in residential areas you should be ok, unless as said you live in an area where they really don't like bikes!
FWIW I also ride around with a black visor, I've spoken to a few cops about this now and because I always have my clear visor with me too, they never have a problem with it - they have all warned me though that if I were wearing it after dark with it down then I would probably end up in a fair bit of trouble should I be caught!
License plates is the one thing I don't muck around with though, my plates are generally a tad smaller than the norm, but the actual spacing and letter sizing is all fine so it's not a problem