Its kind of hard to see here, but the green line is RPM. You can see how fast it ramps up to 7500 (white vertical line) and then it burps and just falls over and slowly climbs to 8000. At the track last time the car ran from 5k to 8500 fast and didn't slow down. I believe what Sam says in that its the C4 and the way a real loose converter acts on the dyno. We have had the car up to 9k before and there wasn't a lag at any point.