What is happening on this dyno? Help

finally get my engine back and went to a dyna pack and strange result..? Engine is 408 w2 ported heads , comp cam , 10,5 i comp, used dynamic converter 9,5 street and strip, stall 3800-4200
Tti headers and 2,5 all the way, 950 holley hp series, good pressure and mix, sooo what is happening at my engine on 5600? Is the converter the trouble? Thanks for help