Yeah when I got Allen to retune(well tried cant do it with bad O2 sensors) my truck for the 418 he is hte one that let me know my needles were off I thought the oil presure was high and the engine temp were off a little but they were off by ALOT. Simpliest way IMO is to do what I was describing otherwise you will have to find someone with HPT to tell you were they should be at for all the gauges.

 

Yeah i did it this morning and got it pretty damn close, the only one that might be off slightly is the oil pressure, possibly a little high.

 

just seeing if this works