I drank the Kool-aid on these coils several years ago and they didn't work for me $$$$ down the drain in my opinion.
http://www.takai-racing.com/main/ignition_coils.htm
They didn't fit correctly because you need the extenders to get them to clear the valve covers. Then the extenders would get stuck on the plugs. Then the boots would get stuck on the plugs so you couldn't the plugs out without tearing the boots in two. I dicked with them for a while. So finally I get a chance to compare them on the dyno, same day, same plugs, same fuel etc. dropped 7 hp, WTF? Nels said they "may" eventually work the same as stock if we played with dwell and such. By then I was done with them.
Some of the fastest turbo bikes I know of are using the stock coils or CBR600 coils.