Is my bike getting good MPG

[JoeRock]

Whilst your on a restricted licence I'd leave the k&N out. If you get stopped or heaven forbid are in an accident and they find out about the air filter being a performance upgrade, your in a world of pain from both the law and the insurance company.

Basically your airfilter could in theory take you over the 33bhp limit, which invalidates your insurance, which means at the roadside your bike gets siezed, you also get 6 points/£200 fine, and taken to court for driving other than in accordance with a licence where another 3 points minimum and another fine. That's your licence gone. Then you have to get someone to insure your bike, pay the £150 recovery cost, and the £15-£20 per day storage costs.

Don't put performance upgrades on a resticted bike, it just ain't worth it!!. Standard filters are just as good for now.

Can't see that happening, the restrictions block off the carb inlets, so blocking the amount of air/fuel mixture that goes into the carbs, changing the filters barely going to change that - just might make it run a fraction leaner in the revs that the restriction allows. BIke could theoretically be siezed at the side of the road, but only reason that's going to happen is if the police a.) know that you should be on a restricted license, and the vast majority don't know about that, and b.) have reason to suspect your bike isn't restricted, which is only going to be the case if you blow past them at somethig like 120mph +
FWIW, I've had K&N's in all my bikes as they usually give a little more power when the jettings altered to suit. Only one I took it back out of was my ZX9R, as it played up with the ram air on it.
I also had a restricted bike which the restrictors fell out of after about 6 months, had a non-fault accident and they didn't even check. Had a bunch of mates do the exact same thing, and nothings ever happened to them either!