Just a couple of questions about hids

1. I got my kit this morning 50w 6000k, one of the warning cancellor capacitors was missing, i have tried fitting them with and without it and both ways worked without strobing or flickering. Do i need then fitted or not, what would yo do?

2. Both of the ballast boxes buzz when the lights are switched on is this normal or is something wrong with then?does this stop when the engine is running?

Thanks