My boss's new 2004 GMC LLY CC D/A 4x4 Dually is coming in Tuesday and he is going to be doing some mods to it. He doesn't want to get to radical with it, but wants a little more power. We work on offshore powerboats and most of the time this truck is on the road it will have up to a 50' 20,000 lbs. boat behind it. I just want to know a few different upgrades that can be done to the truck so that it can have a few more ponies, but not void the warranty or need a tranny upgrade. I was hoping he could stick with a chip or programmer, exhaust, and a new intake system, but I don't know as much about this as you guys so a little help would be much appreciated.

No computer performance upgrades on the market yet for the LLY engine. Some in test stages though. Sounds like could be awhile till the new products are fully tested and released.


Exhaust upgrades are available. Though questions are out their about their effect on the EGR system on the new diesel, may trip enigine light with exhaust upgrade.


Don't know of air filter upgrades yet, I have not researched them. I am erroring on the side of qaution with the new variable vane turbo for now.


I towed my heaviest load this weekend a JD tractor which I'm guessing pushed 8-9 k. Could of put the truck on cruise, the most power I've ever had in reserve versus my previous diesels.


http://www.dieselplace.com/forum/uploads/E56_IMG_3489A.jpg

My suggestion would be to break-in all related parts, ie. differential, tranny and engine. Then change the fluids of all with recommended oils of your choice. Decide on synthetics or dino oil. Read up on the forums on each make up your own mind.


There are upgrades coming in the next months so be patient and stick to upgrading the oil filtering system, and the fuel filtering system, you can get a deep sump pan and filter system for your allison if that is what you have. The allison deep pan is 200. cheaper than the aluminum finned pans. If you use one of the recommended allison oils and deep pan your tranny will run cooler and your capacity goes up 2-3 qts. Many people like the fumoto valve for their drain plug.


Check with all the popular chip company, exhaust company, intake company websites periodically and they usually have a special note relating to the lly engine upgrades.


I have a beta Edge Juice and Attitude for the lly coming to test and give feedback. Just remember power at the cost of durability can be expensive.