Lowering the front is easy and free - and improves handling. You can lower it at least 20mm with no problems. Lift the front of the bike, unloading the forks - I do that by putting it on a rear stand and then lifting with a car jack under the crankcase right behind the oil filter. Have someone help you to prevent it from falling. Loosen the bolts that clamp the triples (and clip-ons if you have an "S") and move the fork legs up. Make sure to measure precisely so you move them the same amount. If you go further than 20mm, make sure the fender doesn't hit the radiator when the forks are fully compressed.
Personally I wouldn't lower the rear, is bad for the handling...