Out of pure curiosity, did you have to order that rig or was it on a lot? My understanding is the current MegaCab trucks are order only. And is it still basically a 2500 with the solid front axle and no MDS just like the generations before?
That being said, in all my research of the current HEMI motor (I have an 07) there is no major power adders or upgrades. Little things like intake and exhaust can help buy not much. The tuners don't do much either as the motor is pretty fine tuned from Dodge already. I've read some folks who did headers noticed increases also but on these trucks it is not a simple install. I do know that major mods like upgrading the heads have been popular, going to the SRT heads.