Air is the way to go..You can control opening and closing rate with air not with electric. Some cars dont like to just come off instantly from the stop. My car has the bleed valve almost closed and comes open VERY slowly. Takes just under 2 seconds to come open fully.

I have used both the disc and butterfly versions. On my car we are able to close down the disc more so I can get less down power RPM. On the buterly I was only able to get down to 4300 and make the car happy. With the disc we are at 3700. The idea is on as quick as possible as low as possible to maintain as much MPH as possible.

Can get a little more in depth if anyone cares to. But I think that gives you the jist..Oh yeah went to finals with either stop...