OK...so here's the next set of mods.
I purchased a couple of items for the truck. First, a simple drop in K&N filter. I'll use this for now until I decide what intake to go with.
Next, I went to my favorite speed and tuning shop in Portland, Performance Race Engineering. They tuned my SRT8 last year with great results.
I dropped in the filter then the great guys at PRE strapped the Ram to the dyno.
We did a baseline dyno pull and all I gotta say is ugh...what a dog...LOL Here's how they strapped it down in the back.
I had made arrangements to upgrade the truck and they had the tools ready, a DiabloSport Predator U7137:
I wasn't looking to get a lot of HP but did want some more torque and better driveability. I also wanted to correct the speedo error for the larger wheels and tires. I got all of that for sure and one other bonus feature, better shifting with a bit of an increase in transmission line pressure.
Here's the dyno charts. I saw a HP and torque increases across the board, it comes on a bit sooner and my Air/Fuel ratio is now spot on.
I'm seeing more HP and torque at lower RPM's so that's a good thing!
Now, Air / Fuel Ratio. This was important to me as I know how lean a stock engine runs. For those of you not up on the term, it simply means how much fuel is being fed into the engine in relation (ratio) to how much air.
The 5.7L HEMI (and 6.1L for that matter) stock program runs at 14.1 A/F in static mode, i.e., when at idle or at steady state cruise. 14.1 A/F is a lean mixture, i.e., lower fuel to air ratio. Lean is good for mileage, not good for power. The stock program will add fuel to the mix as the engine demands but it does not always add enough to hit optimum A/F for power. And it waits a long time before it does it, keeping the engine lean at WOT for too long, robbing it of power and inducing knock retard.
The HEMI seems to like a 12.5 to 12.8 A/F.
Therefore, your HEMI is pretty close to reading knock at WOT and the computer will pull fuel and timing to avoid engine damage. The MOPAR stock program is pretty conservative and aggressive with respects to knock retard.
With the Predator 91 octane tune installed, A/F improves considerably and gets it into the "sweet spot" for the HEMI. What's cool about the Predator tool is that if the canned tunes don't get you there, there's an option to add (if it's still in a lean condition) or delete fuel (if it's too rich - haven't seen that happen much with a stock program on the HEMI) to hit the sweet spot.
In the chart below, the line that starts right at the 14.1 measurement is the stock program. It almost stays there the entire time and it's way too lean. It dropped down below 12 way up in the RPM range. That means it was running lean almost to redline and it was knocking, then it got very rich.
The line above that, starting at around 14.6 A/F, is the Predator tune measurement. It starts to drop almost immediately and hits the sweet spot right at where the engine is designed make max HP. I won't have to add any more fuel.
So, in perusing the dyno sheet carefully, the truck went from 240 lb ft @ 4800 rpm to 295 lb ft @ 3750 rpm (that's 55 lb ft improvement and it comes lower) and from 230 hp @ 4800 to 275 HP @ 3400 (that's 45 HP improvement and it comes lower in the rpm band).
Anyway, enough of the technical discourse, here's the chart.
All in all, I'm very happy with the results. Eventually, I'll go back to PRE and get a CMR tune for some fine tweaking and more power.