For 5/8" wood stock, cut a 4.5" diameter port hole.
For 3/4" stock, cut a 4.625" hole.
For 1", cut the hole 4.75" diameter.
For 1.5", cut the hole 5.125".You can order the tweeters on the shopping cart in the "Parts and Options" section. Look for the "Vifa Upgrade Kit". That kit includes a Vifa DX25 tweeter, Solen 10uF capacitor, 16Ω, 10W non-inductive resistor and two spade lugs.