We use these almost exclusively for starting our Q-500 and Q-40 racing engines (when the timer is running, it really helps to have a
good hot plug). They aren't cheap ($65-75) but I find myself using it when ever I can, as long as I'm not starting an in-cowl engine where I need the extension to reach the plug. Thet really do work! If your engine becomes a bit flooded, the driver senses the impedence change and boosts the amperage to keep the glow element hot. They are wonderful tools!

Here is one place to get them....but don't think they are for racing only.

http://www.darrolcady.com/Accessorie...Pro-driver-pic