I have a new UNUSED 14T sprocket if u would like to buy it...

less teeth on the sprocket puts more stress on your chain

www.sprocketspecialists.com  

I have a 14T front but don't know the top speed. But is also dependent on what size rear sprocket you have as well.

It also depends on your bike have 2 gs's one does about 95MPH WITH 14 the other over 100MPH the faster bike being older.
but try it as they pull away from lights well   also if you do long trips or fast roads it will feel like it wants another gear.
have left 14 on older bike and 15 on newer ( only 2 yr between bikes ) younger bike gets used for long trips other for short.