The additive helps, had it in the Stang for about five months. Recently got around to installing my MGW shifer (awesome), that with the additive really made it as good as can be. I recommend that it be added regardless of shifter as it does make a little bit of a difference.
2012 Mustang GT Premium --- Red Candy
MT82 --- MGW Shifter
3.73s --- SR Performance Strut Tower Brace
Borla-S Axle Backs --- Boom
Black Bullets with Polished Lip
Raxiom Tinted Tail Lights