6" lift on 2003 GMC sierra 2500HD

Hey. I am wanting to put a 6" tough country suspension lift on my truck. just would like some additional information of the consequences of putting them on. What does it affect? I tow more than occationally, and like to do some off roading.
i would also replace my 33"x12.5", 17" rims with new 35" tires, while keeping the same rims.
So any help on the overall more than normal stock wear and that kinda stuff would be awesome. Thanks  
Excuse me.....Do You Like Country Music. DB

Lift and tires is bad for serious towing. It raises CG and use of a offset hitch to make it the correct tow height WEAKENING hitch capacity because of added/increased leverage it places on hitch and frame. This aside, lift and big tires will greatly reduce towing power because it makes effective gear ratio taller which means you know have LESS power to power truck at any given speed and it takes more to move it because of lift and added drag before you even add a trailer. Anyone that tells you that you can fix this with a tune (air filter or dual exhaust) is blowing smoke at you big time. You need to regear truck with about 4.88's with 35's (if you plan to tow 6K plus better figure on maybe 5.13's) Failure to do this will not only result in slug like performance, frequent downshifts, poor MPG but can also result in shorter tranny life too.  

I am in full agreeance with snoman. If towing is the main concern don't lift it, with that sort of lift a goosneck will be much more a pain in the but.  

I agree with the others about towing
Also you will see increase wear on your hub bearings and steering linkage
You also need to install a auxilary transmission cooler the bigger the better  

if you regear and when you lift and do it right you can tow fine. i have a 03 gmc duramax with a 6 inch and 33 x 15.5r18 mickey mtz's on it and have a bullydog programmer and regearer 4.65s and tow a gooseneck fine. hauled 12000 pounds the other weekend a hundred miles no big deal. just have to build the truck right  

Ofcourse moderation does come into play here... 33's aren't very big... Gearing will help but even then with large tires and a high lift its still going to strain parts. If your just towing with it on highway there is no reason to lift it. If you are doing light towing off road then keep it as low as possible with some good tires on it.  

There are many websites on line that have great charts that show tire to gear ratio and where they are performance wise. I use this one. I tend to stay in the factory settings zone. You'll see what I mean by looking at the chart. http://www.4lo.com/calc/geartable.htm  

okay so why 4.88??? WITH 35in tires whats wrong with a 4.10??? THERE IS NO WAY YOU WILL NEED ANYTHING TALLER THAN A 4.10 especially if your truck is a diesel... THE DIESEL IS ALREADY PUSHIN MORE TORQUE THAN A GASOLINE ENGINE. I HAVE A DODGE RAMCHARGER WITH A 6" LIFT SITTING ON 37's AND GEARING IT WITH 4.88's YOU NEED TO CALCULATE YOUR RPMS... THERE IS A WEBSITE ITS WWW.JAWSGEAR.COM  IT HAS A CALCULATOR WHICH ESTIMATES YOUR RPM FOR TIRE SIZE AND GEAR RATIO... FOR MAXIMUM OUTCOME IT WILL HELP YOU FIGURE WHAT GEARS TO USE WITH YOUR TIRE SIZE. I BELIEVE YOUR RECCOMMENDED RPM WOULD BE AROUND 1800-2200 WITH 4.10'S AT 65MPH YOU WILL BE AROUND 1900... WHICH IS IN BETWEEN UR RECCOMMENDED RPM WHICH IS FINE. OR WITH 4.88'S SOME MPH YOU WILL BE AROUND 2250!! WHICH IS ABOVE YOUR RECCOMENDED RPM DO YOU WANT TO LISTEN TO THE IDIOT SAYIN 5.13'S??? YOU WILL GOIN DOWN THE FREEWAY 65MPH GUZZLING FUEL AT 2368!!! IDIOT YOU WILL BE FINE WITH 4.10'S OR I'M GUESSING YOU HAVE 3.73'S NOW IT WILL NOT HAVE POWER BUT YOU WILL GET BETTER MILEAGE ON THE FREEWAY BUT CRAPPY TOWING AND AROUND TOWN.  

hey idiot if he regears with a set of 4.56's or 4.88's he will be running about the same rpm with the 35's. if he doesn't regear the truck for the bigger tires it will kill the tranny  

Dudes,
 I have a 2002 GMC Sierra HD with the 8.1. I have the 6" lift, 35" tire. 4.56 gears and  usually tow about 12000 lbs every weekend. Yes I do have all the other dod das, exhaut, mufflers, k&n, hypertech, Allison tranny. And no matter what my gpm sucks.