My favorite mod was the after market rotors for the dually. 

cowgirl98034, Chips do increase power, but a chip it can void your warranty and it can also shorten the life of your engine.  Also if you chip your truck be sure to get a set of gauges.

We hated the brakes that came on our dually.  The aftermarket rotors are great, truck stops better and smoother and we have not had any overheating problems since then.

Reg -- Our Dually has *never* been overloaded, unless you think 10,000 pounds is too much for a dually.  The brakes on the Ford Dually's have been a problem on the 7.3 liter model trucks (I'm not sure if they fixed the problem on the more recent models).  We had overheating problems, even without the trailer.   In our 20+ years of towing, this is the first vehicle we ever had brake problems with.  When the truck was new, we had the truck in to the dealer numerous times (the first time at 4,000 miles), because it took so much effort to get the truck to stop, the dealer said everything was fine.  Once the after market rotors were installed the truck finally stopped like it should and as I mentioned the overheating issues dissapeared. 

And no I don't sell them and I don't review them for magazine articles.

I review them. It's true, the rotors that come on new trucks the last few years are crap. Sometimes the same model year will have 3 different Chinese manufactures. We pull bigger trailers each year. It's a safety issue, but for towing often, replacing the factory rotors and pads is an excellent idea. I'm all for replacing magnet drum brakes on horse trailers too with hydraulic discs. We just did that on our Hart Horse Trailer Safety and Tech Tour and it's unbelievable improvement. I'll have an article out with the results. Next weekend the tour is at the Minnesota Horse Expo, stop by and see the brakes and hydraulic actuator.

My hitch receiver is my fav truck mod:

Well, Here ya go. I just got mine a few weeks ago from here.

http://www.drperformance.com/brakesmarthome.html

The BrakeSmart controller would fall into the "you get what you pay for" category. It is truly that good. I had a Prodigy and while better that the rest of the inertia controllers, it can't hold a candle to the BrakeSmart unit.

The biggest difference is below 20 mph. Ever gotten to an intersection at 10 mph, step on the brakes and find yourself skating on pea gravel because the truck was doing all the work....the Brakesmart eliminates this issue as it brakes the trailer in proportion to the peddle pressure no matter what the speed. Most any brake box will handle going from 65 to 30 in a hurry.

The closest I ever came to having a wreck was at 15 mph.

If you ever go down a grade loaded with an exhaust brake you'll never want it any other way. Mine wasn't a mod, it came on my medium duty. I thought it was pretty cool just driving around here but when I pulled in the mountains the first time I fell in LOVE with it. Coming back down Black Mountain (6% grade) with a fully loaded trailer I only had to tap my "real" brakes twice. No sweaty palms and niggling doubts. I'm sorry but I rarely drive in the mountains and I'd never before been completely comfortable pulling a trailer down that grade. Maybe I don't actually NEED the exhaust brake but it sure made me feel better.  Just lay off the gas, the truck is set to automatically downshift and it was smooth sailing all the way to the bottom. All I had to do was steer Very cool!

been thinking about this for 3 weeks.......but no ive never had any problem with my prodigy under 20 mph.  matter of fact there was still a stain on the passenger side floorboard of the trailblazer where my wife dropped her drink when i was still fine tuneing the prodigy.  we were in a parking lot, ~15 mph and i applied the brake in a "normal" stop......nearly put us both in the windshield.  tweaked it a few more times and if worked perfectly at all speeds. of course not all rigs are the same, this trailer has outstanding brakes. some other ive had have not been so impressive.  another observation, this same trailer, now being pulled by the dmax, has far less ability to slow the truck (almost 3000 pounds heavier than the trailblazer). as such i had a time with smoking tires at the same settings i had used on the trailblazer.

im not doubting your account, nor am i disputing the brakesmart is better.  the pricipal it works on is without a doubt better.  but is it 4x better?  personally i doubt it, ive got a p3 on order.......just might get around to a brakesmart one day.