Okay - several things here.  Yes, pulling power is a good thing - so is
stopping power.  The 3rd gen Rams have some great brakes - however, I'd
definitely want an exhaust brake when pulling that kind of load.  Your
truck's computer isn't exhaust-brake-aware, and an upgrade (though promised
by DC) isn't available yet.  Since you asked about turning up the engine's
power, we can assume you're cool with throwing caution to the wind, and
assuming warranty responsibilities.

With that, I'd suggest some mild tranny upgrades.  I'm an ATS guy when it
comes to transmissions (others have their preferences, but I've flogged the
ever-lovin' crap out of mine, without much of a problem).  If you go with
their torque converter (IMO, the only "weak link" left in the factory 48RE
setup) and valve body, along with their ATS Commander (may have changed the
name of that - the electronic controller), you'll have what you need to run
an exhaust brake.  Their box can talk to your exhaust brake controller, and
make sure the brake disengages if/when the TCC unlocks (though, with their
control box, you can maintain lockup all the way down to 4MPH, if you so
desired - it's adjustable).  In the ATS world, that's their "Stage 3" (or
Option 3) selection, for about $2,700.  Add another $1,000 for an exhaust
brake.  I'd also throw in a few hundred $$$ for the Mag-Hytec double-deep
tranny pan.  It provides better cooling, and more fluid capacity (which is
also better for cooling).

For the power side, I still think TST is the best in the business.  Their
latest revision of their Powermax box has plenty of bells and whistles...
two user adjustable fueling curves (both low-RPM and high-RPM curves),
user-adjustable fuel pressure (I don't recommend going too much over stock
pressure, if at all - but the option's there), user-adjustable timing
(really only useful if using it in conjunction with other boxes, but hey -
it's there), and built-in protection (defueling) based on EGT's and boost
pressure.  There's also a built-in cool-down timer (you can turn the
ignition off and lock up the truck - it'll continue to idle until a preset
temp. or time limit, then shut the truck off).  It gives you digital EGT and
boost gauges, a rail pressure gauge (useful if you're going to muck with
fuel pressure), and comes with four different base programs (three
performance programs, one fuel economy program).  For $900, it's all you'll
ever need in the way of boxes or programmers - good for anywhere from stock
to 600HP at the wheels (and I got the dyno sheets to prove it!  :)  Now, you
can't get that kind of power just by throwing this box on there (well, you
could, but without a better intake, bigger/free-flow exhaust, and larger
turbo, you'd melt the engine in short order), but the point is it's got the
ability to deliver.

With the added power, I don't think a gear swap would be necessary.  With a
manual, I might think differently, but the auto gives you a little more
flexibility in that area.

In addition,  I'd definitely recommend a trans temp gauge.  They go for
about $55.  I also recommend installing the sensor in the return line from
the cooler.  If you've got a flaring tool and get some AN fittings, you can
do this yourself - otherwise, I recommend a $75 replacement cooler line from
Mass Diesel that has the port already installed.

So, for about $5K, you can set your truck up to pull (and stop) your trailer
comfortably.  Yeah, a 6spd auto would be nice...  the 6.7L engine would be
nice...  but I don't think you're going to do better than $5K on a trade-in.

please see http://inlinediesel.com/forum/topic.asp?TOPIC_ID=617 and give me
your feedback and advice.
thanks,