First off thanks for having me on this forum. What an incredible resource!! I just recently purchased a 2003 Chevy duramax dually with a flat bed that I plan on using for towing boats. I just got back from a trip to Nova Scotia towing a 33 foot boat (15,000 lbs) and the truck handled great. I plan on towing a lot more and to that general area so travelling on hills and mountains will be frequent. Long trips are the norm and I like to keep up with traffic (70-75mph). What modifications would you suggest to the truck(motor,chips,tuners,exhaust,guages,fuel system,transmission,etc). Also any pointers or any info you would like to share would be greatly appreciated. I apoligize if these questions have already been asked.

a tune is going to be very beneficial. however if your towing heavy or hot-rodding your trans will need an upgrade soon. a turbo back exhaust system will greatly lower your egts and will help your truck breathe better.

This is only my opinion- I would not do a freaking thing to the truck! These trucks are absolutely awesome and hauling 15k at 70-75 should be no problem!

I'd make sure my fluids were fresh and synthetic in the drivetrain. Chevy notoriously underfills the diffs, for instance...

flush tranny and replace with transynd, boost and egt gauges, remove or replace muffler, bilstein shocks, secondary pre-oem fuel filter, and mod your stock air box.

This is only my opinion- I would not do a freaking thing to the truck! These trucks are absolutely awesome and hauling 15k at 70-75 should be no problem!

Yeah, other than maintanence as the other mentioned, I wouldn't do anything. What you plan on pulling is not out of the norm, particularly on this forum. I would probably slow down a little to get better fuel mileage, but that's me.

I fall in the maintenance items camp including good tires that are not to aggressive. Also make sure you flush/refill the Power Steering / Hydroboost system. Consider adding a PS cooler to prolong fluid life. Tranny cooler maybe be an item to consider -depending on how the temp gauge reads under loads.

I prefer synthetic fluids in everything for your type of usage. If truck was used around town only -I would use Dino motor oil due to short oil change interval issues.

Thanks so much for the input so far. I was kinda leaning towards a chip and exhaust. Any reccomended brands/systems. I have my ideas but I would like a chip that improves towing not just speed. Thanks in advance for your help.

most chips have tow tune settings anyway. hypertech is a very mild tuner that will get you a few mpgs and you can tow at the highest power level.

Make sure your trailer tires can handle that speed. If they are ST rated trailer tires, most are speed limited to 65.

Make sure your trailer tires can handle that speed. If they are ST rated trailer tires, most are speed limited to 65.

Very good point and will be an unknown variable towing contract loads.

I'd suggest a chip and 4" turbo back straight pipe to control EGTs. As far as comfort, I'd also recommend air bags and an auxiliary tank. If you are pulling a lot is is always nice to get more than a 300 mile range.

Also tow a 5th wheel on long hauls and some trips with the boat taging along. :D
I made changes to my air and exhaust. However a good 4" exhaust system will make the most difference.
Extra fuel capacity would also be a + on many trips.

Boats always seem to have more wind drag at speed than other loads due to the railings, antennas, etc. In my experience, a tow tune is much more comfortable when dragging a boat around 70mph since they allow you to stay in overdrive more.

In stock form it will work OK. I'd get a simple chip {Predator,Edge Juice,Hypertec,PPE standard,ect along with some form of guages to moniter EGT's and boost. You'll need a good 4" turbo back exhaust too. I recomend air bags but they aren't needed on a dually. That would be a great start.