From my limited experience so far with my 2010 SXT I can tell you the following.
The CAI, 71mm throttle body more than likely have messed with your fuel/air ratio and is probably making your car run rich. Which in itself is why your low end is suffering and your high end is pulling hard.
I had my SXT dyno'd stock, 168 rwhp, (I believe, I have not posted everything yet, waiting for my last tune session and dyno to post all my results) at right around 75,000 miles.
First thing I did put on my AEM CAI. Re-dyno'd and actually lost hp (156 rwhp or so I believe) and performance (could tell by just driving it). The tuner at the dyno shop said my fuel/air ratio had changed and was running too rich from the stock run.
So I ran out and bought a Diablo Intune, installed a Dynomax VT muffler (mine was shot), and Blastin Bob's 14 db reso kit exhaust.
Took it back to the dnyo shop and had it tuned (to correct the fuel/air ratio using the Intune) and then ran another dyno run. Now it did 197.5 rwhp. Let me tell you it was fun to drive. I had the throttle set to +1.5 in the Intune and my car pulled hard from start all the way up to red line. I bumped the throttle in the Intune up to +5, and could hardly keep the tires from spinning every time I took off.
Next in the series. I ordered BND (brians) oil and filter, and aces IV gas additive. Changed the oil & filter and added the aces IV to my next fill up. I did nothing else but those 2 things. Ran 3/4 of a tank of gas and my car started acting up after the fast idle shut off upon start up. It would not idle right and would idle up and down enough that you could clearly hear it from the exhaust.
After 2 days of this it started throwing p050b code. (which is idle failure) So after talking to Brian and him explaining what the aces IV is suppose to do to cleaning and lubricating the engine, I re-installed the stock tune and per Brian's advice am running 3 tank fulls of gas through my car before having it tuned and dyno'd again. I just filled up the 3rd tank yesterday, so when I am done with this tank I am going back to the dyno shop to have it re-tuned to correct the fuel/air ratio again and to see if I gained any rwhp.
It will be interesting to see if I did gain any rwhp, because all I have done is oil & filter change and add aces IV, nothing else but driving my car. I did order the rear end lubricant yesterday from Brian, but will not put it in till after I dyno my car again. Do not want to scue any of the results.
If your tuner can adjust the fuel/air ratio, I believe mine ran the best at around 12.5 to 12.8 in that range at the dyno shop. My tips also got coated with soot from un-burnt fuel before I had my fuel/air ratio corrected. Then sooted up again after the idle incident, that is part of how I new something was off.
Sorry about the long winded response, hope some of this at least helps.
Just as a side note, I was going to install the 71mm throttle body on my Charger also, but after research found out that it really won't make a difference if you haven't done something to the internal of your engine like a cam to increase air flow. I might just for giggles add the 71mm throttle to my car after this next dyno and then re-dyno it again to see if the 71mm throttle does make a difference or not. Now I am kinda curious.
