I've got a template that fits Type 1 Ghia rotors. It also fits 914 rear rotors, which are the same as most aftermarket kits. It has 48 holes that are the same pattern as what the Japanese motorcycle makers use. It is NOT the silly spiral pattern that everyone uses. Most of those I've seen are drilled wrong. Even some OEM rotors.
When drilled with a ¼" drill, the weight reduction is 113g per rotor. A 3/8" drill gets you 255g.
For you metric heathens, that's .25lb and .56lb.
Beware, when you drill them, they will make a LOT of noise. Think about blowing across the top of a bottle, I think that's what makes the noise as the pad swipes over the holes. The set I drilled with a 3/8" drill were for Larry, and he reported they were so noisy, that he took them off right away. I've got one pair that are with ¼" holes, and I don't like them. I remember after I put them on my car, I was in SoCal soon after. Bill wanted to drive my car to test out the gear ratios I picked for my 5. As soon as we got over about 20mph, he asked if I had drilled rotors. He noticed it right away. If you have solid trans mounts, you're probably going to be ok with the noise. It will be minor by comparision.