I have owned a 71 911T for the last five years, It is used for autocross and someday maybe club racing. My question is is it possible to replace the stock cams with cams from a E? will this make much of a performance difference (I have the stock twin pipe sport muffler)? Will I have enough valve clearance? Does the distributor need to have the advance curve changed? (Bosch dist.) Also the mechanic that rebuilt this engine in the early 90's said he thinks he remembers putting "S" pistons in, it's not that I don't trust him it's just that he did not seem real sure. Is there a way to tell what I have in this car without tearing it apeart? As a shade tree machanic I am greteful to have a forum like this- thank you Justin