Big Gun or White Bros.?

[400exracer511]

I am goin to get a CDI box for my 400ex but dont know which one to get. I have heard that the white bros box makes it hard to start if its cold. which one is better or is there one other than big gun or white bros that is better?

[cals400ex]

most say TC or GT thunder. the GT thunder box will advance the timing 6 degrees though, so it can't be used with the sparks timing key.