I think you just figured out your own problem..... Scott Drake make one and there is a pot internally that allows you to "time" them.
I went through Vic at Cougars Unlimited for my electronics. I wired sequentials into my Shelby. I hate the Dynamite sticks and others that sequence when the brake lights are in operation or the hazards lamps.
You have to be blind to miss the brake and turn signals with the plasma leds.
-Keith