I have been thinking, and I believe the two instances of the CEL coming on were both prior to me swapping out the old air filter for a new one. While changing the oil, I decided to check the air filter which was very dirty. Also, it appeared to be a cheap filter (Purolator or similar). You couldn't see any light through it at all. Also prior to the new air filter, the car seemed to be idling pretty low (slightly under 500 rpm). After replacing the old air filter (I had to get a Purolator because they didn't have the K&N in stock), the car is now at or slightly above 500 rpm idle speed and I haven't had another CEL scenario since (crossing my fingers). I plan on replacing the filter with a K&N as soon as I can get one ordered. Also, I was thinking to check if the car still has the stock fuel pump in the tank. I know that a lot of people recommend replacing the fuel pump with a larger aftermarket pump if there has been significant upgrades to the car's fuel/air system. Additionally, I haven't had a chance to peak at the numbers or stamping on the turbo yet. But, I can tell you that I am boosting consistently between 16-18 psi under hard pedal. I don't know if that helps any of you with what type of ugraded turbo I might have on the car and/or what WHP I might be getting out of the car or not? Also, would replacing engine pulleys (alternator, etc.) with lighter aftermarket pulleys offer any h.p. gains? Or, are they a waste of time and money?