Good to hear you had a good time. It's hard to keep track of the flags, cars in front of you and the cars in back of you while you're driving as fast as you can.
You really need 2 days at a track to really get going. Like you found out, by the end of the first day, you're just getting comfortable with the track. The second day, you start to go fast.
Was there an instructor in the car with you? They should have seen the black flag for you.
Let me get this straight... You are swapping out parts designed by some of the top engineers in the world because some guys sponsored by a company told you it's "better??" But when you ask the same guy about tracking, "oh no, I have a kid now" or "I just detailed my car." or "i just got new tires."