What size hole have you folks been using in the hub cap? I have a 4" hole bit, but that looks a wee bit small.

 

From what I have read, they use a 4" hole saw and go from the inside of the cap, to minimize the chipping on the chrome. Apparently it leaves a small lip you'll have to take down with a rasp or file. Pics I have seen show it fits pretty snug, so you have to get it right. I've been looking at going with the Dynatrac hubs, too.