I leave it on. I like how it revs if I downshift coming to a light next to people
It's also good for when you are getting used to the shifter, you know right away if you're going into the wrong gear (i.e. from 5th to 2nd instead of 5th to 4th) because it will rev immediately as the sensors see you go into that gear.
You can turn it on or off by holding the button down. The button reads "S-MODE" and passengers will say "what's that!" and you have to tell them the boring truth that it doesn't automatically lower the car and turn rocket boosters on
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Pearl White 2010 370Z Sport, Stillen CBE, tint, K&N drop-in filters, GT-R start button, Kenwood DNX-6980 with backup cam, LED bulbs, Raceseng shift knob.