depends on the car every car wont launch well at 3k, but 3-4k seems to be were most do tho. But you just have to practice when ugot o the track. because too many conditions apply. you might be able to dump it higher and get a quicker time with better tires. or you might dump it too high and bog and just burn up your clutch. Its one of those things that can only be learned by trial and error.