Last time I dynoed my rig I put down 476 rwhp on a Mustang dyno in second gear without the torque converter locked up. My question is would I see higher numbers in a third gear pull, torque converter locked and say on a Dynometer??

 

Yes, 3rd gear (assuming your a 4 speed auto, if not what ever gear is 1:1) with the converter locked is like running a manual trans. No more converter slippage.