[tonythetarga]

If you have a choice between a 996 and a 997, you might want to think about the advantages / disadvantages to both. You're learning about the IMS, I see. The '03-'04 model years you mentioned had the IMS with the highest failure rate. If the engine was replaced, you want to know when. What is the actual engine number on the car? If it has an AT in the engine number, then the engine was replaced with the later style IMS bearing, which means you can't replace it without tearing down the engine. That is the same issue with 997's up to MY 2008. After that, they eliminated that style of bearing altogether.
The 'good news' about the 997 style, is that the failure rate is much lower, however, the problem still exists in some small part. Frequent oil changes are more necessary.
The PPI is always a recommendation, but the difference is that you need someone that knows the iterations of the water cooled cars and their issues. I see ads all the time that tout the '05-08 engines as having the 'never worry' IMS bearing. Don't buy it. Just know what you have.
I wanted a Cayman S and bought an '06. It has the non-serviceable IMS, but I've made changes to do as much preventative damage as possible. baffled the oil sump, removed the seal on the IMS and use good oil with frequent changes. Have the oil analyzed every oil change as well.
Good luck!