Porsche engine troubles?
 

my customers have been searching for a car lately, and my customers is considering either an e46 BMW M3, or a 996 Porsche 911 alldata mitchell. however, while searching Ebay, my customers have noticed a lot of these porsches from 1997-1999 have had their engines replaced... Was there a problem with the engine (recalls...), or were the owners just too rough with them?