4% should be fine depending on what you are using the computer for. The more space you leave unpartitoned (over provisioned) the more spare blocks the SSD will have to use but if the computer is just being used as a normal work station 4% is probably plenty.
You may want to turn off disk defrag but other than that I have never really seen much of a performance boost from using any of the other various tweeks. Win 7 is pretty solid for SSD after install with no real tweeks needed.
