Ries Robison

Hello, I have a 2003 3/4 ton suburban with the 8.1L stock engine. I do have a custom tune. I use the truck to pull our 9k lbs travel trailer. I have the Scan Gauge scan tool and I display the "LOD" parameter. From the user guide the "LOD" parameter pulls PID$04 that returns percent of engine loading. When pulling the TT under full throttle (ok maybe 90% throttle) I am only seeing this LOD return value of "50" at ~3200 rpm. The HP parameter also returns ~250 hp. Specs show 8.1L is capable of ~320hp. Is this telling me I am never getting max output of the motor? In general it pulls better than my 5.3 L, but maybe not as good as I would hope. Thanks in advance!!