Cam...?

[Nixon1]

When I bought the car, I was told it has a cam in it... "Two steps up from factory". That's all I was told. He didn't have any more information..not even the manufacturer of it. So..would any of you have any idea as to how mild or wild this might be? Also...does a cam really kick in once the engine warms up? My t-stat is WAY cold and the fan runs 24/7, so the car rarely warms up..but today I was sitting at idle in a traffic line and it got up to somewhere resembling a normal operating temperature and the car started to shake and rpms bounced around between 550 and 750 or so...sounded completely AWESOME, but...I'm wondering if that could've been the cam kicking in or just some engine problems? Didn't throw a check engine light..only throw one when the engine is cold and it's cold outside. Thanks!