Where did you hear this lol?? Yes, even with a stock cam, a custom tune (especially with trans tuning) on these trucks will make a noticeable difference.
^^^THIS^^^
I didn't get a chance to dyno my 2014 with the CAI, exhaust & custom tune from Hemifever but I can pass along that the throttle response was much better, there was more torque and HP available at lower RPM, I got better mileage and the custom tune was head and shoulders above the "canned" tunes that come with the programmer.
I do have dyno sheets on my 2007 5.7L HEMI powered MegaCan. The baseline run was with a CAI & exhaust only, the second run was with the "canned" tunes installed from a Diablosport Predator. You can see more HP & torque coming in at lower RPM and that torque is what moves the vehicle from a dead stop and low speeds.
The other benefit of the canned tune was the truck wasn't running lean at WOT (around A/F 14.x) and it was getting the fuel it needed to avoid pre-detonation and knock retard. If those conditions exist, the computer starts pulling timing and performance drops.
Here is the HP/Torque graph - Blue line is stock, Green line is with canned tunes. HP is the taller line, Torque is the flatter line:
And here is the air/fuel ratio measurement. The Green line is with the tune, the blue line is stock.
Look at where the stock program begins, right at 14.0 A/F. That's lean at idle and that's OK. But...it holds at 14.0 - 14.2 at WOT. Look at it jitter and bounce like it's pulsing fuel, backing off, pulsing, etc... And note that it stays lean until around 4300 RPM when it just DUMPS fuel into the engine and goes from lean to very rich within 500 RPM. Not a very good fuel supply model, IMHO.
In contrast with the canned tuned installed, as engine load increases, fuel delivery increases concurrently providing adequate fuel to keep the A/F lower. So now it's not running lean, nor is it running rich. Rather, it is at the A/F sweet spot a lot of tuners look for in a stock HEMI engine, 12.8 to 12.5 and supply is linear with no dumping of fuel.
I tell ya, my MegaCan was a fun truck to drive, it ran well and having the mods noted above made it that way.
Don't even get me started on the tune that's in the SRT8...
