Because people always want the latest and greatest. Also, Nova just loves to keep coming out with specialized bearings so you have to buy their super expensive ones instead of some cheap aftermarket ones. I bet they make more money selling one bearing than they do two engines.

All manufacturers do this. They will make some very minor changes, slap a new name on it and market it as the latest, greatest, bestest thing the world has ever seen despite the fact that it is at best only marginally better than the previous one. Eventually someone in the R&D comes up with something good and we get an all new product, which will then be marginally developed over the next few years.

The bottom line is that there is very little performance difference between a top of the line motor today and one from twelve years ago. An original P5 or WS7 or comparable motor is just as capable of winning today as anything else on the market.