Flat-tappets still work quite well and can produce nearly as much power if matched to the heads, intake and exhaust properly. The big thing when using flat-tappet cams these days is to buy oil that's made for them. I have a Lunati cam in my GTO (with a Victor intake and Doug's Headers). The twin-engine boat I sold a couple years back had Iskenderian flat-tappets that they ground to my specs.
