Those number do not sound even close to correct for a H/C 6.0 LS engine. I find it extremely hard to believe the gas mileage deal either if his tune is right, especially not with your gearing. Those numbers are more like bone stock or minor bolt on numbers, not H/C numbers.
Stock numbers are:
The Gen III LQ4 300 horsepower at 4400 RPM and 360 lb-ft at 4000 RPM, while the LQ9 was rated at 345 hp at 5200 RPM and 380 lb-ft of torque at 4000 RPM.
Something critical is missing or is just BS. I have been around way too many LS combos from mild to wild to buy what your saying as truth.
Or someone just can't build a combo worth a crap and slapped some **** together not knowing WTF they were doing.
Actually you do not know what you are talking about.
What bone stock LQ4 have you seen make 345 RWHP?
They make more like 240-260 RWHP depending on the year.
H/C 6.0L makes about 450-470 hp at the crank? Through a 4L80E 350 rwhp is about the ballpark of where it should be. 4L80E driveline will eat about 25%. 345 rwhp /.75 = 460 fwhp
His efficiency is ruined by the cam and loose converter. My smaller cam and tighter converter along with the lower gear mean my engine does not work as hard to move the thing. I also make ALOT more torque off-idle and into the midrange than his 6.0L does which means I am not stepping on the gas as hard or turning the RPM he does everytime I want to move in traffic.
My RPM on the highway is only 300 rpm higher than his, but I have less engine load. I run lean cruise at 16.5:1 air/fuel ratio at a steady 70 mph.
Also with the gearing and torque curve of the 350 in my setup I beat him to 60. Shifting at 6,000 rpm my first gear is good to 45 mph and 2nd to 75 mph. Shifting at 6,500 rpm his 1st gear is good to 57 mph and 2nd to 94 mph. To get up into his powerband he has get moving to a higher road speed than I do. I actually stay out in front of him up to about 80 mph.
I think his truck would perform DRASTICALLY BETTER with a 4.56 gear and those 28" tall tires. I ran that exact same combination on my 2006 Hemi Ram quad cab when I had it. That truck ran a best of 8.30 @ 82 mph in the 1/8. It also ran 8.50s and 8.60s on 32" tall 20s.
I think my irritation here is that everybody thinks just throw a LS in it and it will get 1,000 hp and 40 mpg and 9 second 1/4 mile.