Ha... Dont give up man.. Just keep at it.. It will eventually work it self out...

 

Did you ever figure out what your problem was? My truck is low on power as well. The highest I have ever seen my Interceptor Scan guage read is 305 at the flywheel. I know these guages are not that accurate, but even if its 50hp off it seems way low to what other people post. HP shows 593 torque at the flywheel and 1/4 mile times about 91 mph.

 

Nope. Never figured it out. Tried uping the boost a bit to see and only got to about 334HP @ 9-10 lbs. Tried increasing the spark advance but then the knock sensors went off. It was false so we detuned the sensors and then power picked up but engine was heat soaked by that time.

 

I know this is an old thread, but I have a couple of thoughts:

Was this a dynojet or mustang dyno? The mustang is a loaded unit. Typically, the mustang dyno will show a lower dyno number, but more in line with what you'd have on the street.

Were these pulls made in 2nd gear? I've often seen 4x4 trucks dyno'd in 2nd gear instead of 3rd because of the larger tires and speed limiter. 2nd gear pulls usually show a lower dyno number.

Do you recall if they used a tailpipe oxygen sensor? I've seen conflicting info on those tsilpipe O2 sensors that many shops have. Personally, I think they would react slower and be much more prone to outside contamination than a sensor inserted into a bung. Once shop I saw recently said take a full point off the O2 readings to compensate for the tailpipe sensor. You could be running too rich. As stated in the opening post, the magnusson tune only showed 13:1 AFR, when they usually have it running richer than 12:1.