We're not talking about 3V heads. We're talking about 2V SOHC heads. And while I am sure there are improvements to be had. With the restrictions just 2 valves place on power production, the OEM PI heads are plenty sufficent for pretty much everyone. And if you need a bit more you get ported PI's. Ifyou need more than that, you'll have to wait till enough other people need more than that to justify the development costs. I have seen data that both supports and refutes this claim. No one said that the precedent hasn't been set. I merely pointed out that the OEM heads are more than sufficent for serious ammounts of power. Ported OEM heads even more so. They still make those parts because, believe it or not, people hot rod things other than Mustangs. Those manifolds and heads are reworks of existing Hi-Po parts. Parts development for late model cars has 2 very large hurdles to face. 1.) The OEM parts are so much better now than they where even 10 years ago it's sickening. Higher quality from the factory limits the aftermarkets abillity to cheaply develop and produce new parts that produce enough extra power to justify the expensive of development and the average guy's willingness to pay for it. If it costs $1 million to design, develop and bring to market cylinder heads that add just 20 or 25 hp and you have to sell them for $1600/pr to make a profit, how many people are gonna pay that? I sure wouldn't. the cost vs power gain is not big enough. 2.) Late model parts are not very marketable if the emissions end of htigns isn't taken into perspective and it's expensive and time consumming to get a CARB# for a part. Those Olds and AMC parts, for example, pre-date emissions testing in most every state so the wide open market still exists for them. The market is more narrow for Late Model go-fast parts. Makes them less profitable and froma business standpoint more risky with less return.