I have tuned this combo in the past and it should go mid 11's.

This car went 11.7 (11.8 in this post)on Nitto's with a crappy 60'
http://www.challengertalk.com/forums/f100/stock-block-5-7-magnacharger-11s-46355/

Not sure about the RWHP # you posted. Maybe that was that on a Dynojet dyno?

In any event I would be glad to take a look at the logs and tune file for this car (assuming it was tuned with a Diablosport product) and make suggestions/changes if you are interested.