When we did the dyno, the u-joint broke on the 2nd pull, turning loose the drive shaft at around 6ooo rpm, luckily I had a loop to minimize the damage. We didn't get any readings. The guy doing the dyno said he thought it was around 500 hp, just by his experience. Had the car on the track, went 111 @ 12.5. On that run, had some wheel spin and have since upgraded the Holley carb from a 750 vac sec to a Holley 800 DP, feel confident I will be low 12's next trip.