~2000-2005 Porsches, the risk of IMS bearing failure wrecking the motor is/was very real. ~10% failure rate by 90k miles. That's a LOT.
A really *really* dumb design decision, to use the same casting for both heads, required an intermediate shaft to run through the engine as cam drive for one head was at the transmission end. After a whole buncha wrecked engines that they did everything they could to not stand behind (had to be class-action sued by a mass of rightfully pissed Porsche owners), they *finally* eliminated this ridiculous and unnecessary shaft and its failure-prone bearing in 2009.
Pre-2000 996s and boxsters had a dual-row version of the bearing which apparently was more robust. And from 2006 on they went to a larger single-row which also had a much lower failure rate. But still could fail and wreck a very expensive engine... When I was looking at Caymans I finally decided that 987.2 was the only way to go to be sure. Then I bought BRZ instead
