First of all, listen to George and get those O2's in the right locations and working properly and get it tuned right. The Dyno Ur using is only a tuning tool, so dont focus too much on the peak number this one tells u as long as the power increases as he makes improvements to the tune. Just a rough calculation, at 8psi, ur motor should make aprox 525hp on a stock 6.0. That translates to aprox 420hp to the rear wheels. I'm sure once u get all the bugs sorted out it should work fine. My truck worked like **** when i first got it on the road but once i got all the tuning sorted out, im breaking the tires loose at 70mph on 14psi (stock 342 gears) .

 

I would be interested in the temperature/humidity/elevation that you were seeing those numbers at. Like someone said the dyno is a tuning tool. Look how many issues you're finding already. You should ask your tuner what kind of timing he has in it, thats the all important number these days. Timing makes power. 0-5 degrees of timing vs 15 is HUGE. I have had my own vehicle turn into a giant turd and found out that the knock retard was pulling ten degrees of timing out. Power difference is huge. Just something you have to play with to find what your combo likes or will tolerate.

Good example, I built a 76mm turbo'd 370 for a buddy in a tahoe. I could only get it to about 2 degrees of timing on premium pump gas and 12 lbs of boost. I got him to put meth injection on it, and I added ten degrees of timing and 2 pulls later we were laughing our asses off from the huge power difference and didnt even care that we just ruined the built 4l60e in 2 pulls with some power. It went from a turd to a Rocket

 

The truck has stock 373s and I actually don't remember the tire size off hand.

I'm going to pick up the truck today or Monday. Tuner messed around with it some more and got 450/470 @ 10psi which seems reasonable. Only thing I'm aware that he did was go through the box of Wastegate springs until he found a good one and put a new boost controller on.

Im assuming the o2 sensor situation is the same. If that's the case then I will I will move the one o2 sensor over to the driver side and have them turned back on afterwards.

Temperature have been low 60s and humidity relatively low as well, my location is about 50ft above sea level. I'm not sure on the timing degree but I'll ask. Is there anything else I should ask when I pick it up as well?

Also does meth injection work that well and is it something I should look into?

 

I was trying to find what Cam set up you had and saw you had stock cam and springs. At the least put some LS6 springs in it. $70 still I think. Meth injection is pretty awesome, it opens the window to really play with increased timing and boost. Very beneficial when towing also or in high temperature or humidity.