I am wanting to tune up my new 95 SL. Quick questions. Best type of spark plugs? (iridium, platinum, and brand). Spark plug wires? Also with the brakes pad brands and does changing to slotted and drilled rotors make a big difference? If so does the brand make a difference? I have a K&N filter, how much better HP and gas milage if I upgrage the intake arm and filter?