Performance Upgrades?
 

I'd like to get some input on some possible performance upgrades for these two vehicles:

2006 GMC 2500HD 6.6 Duramax. Everything stock except 265 tires. It has 93,000 miles, so that means it will be out of warranty in 7000 miles! What are some cost efficient ways to boost power and torque for towing? Usually this is used to tow a 32ft gooseneck horse trailer. I was thinking that a bullydog programmer would be in order, but was unsure of what kind of gains to expect form these without any other performance mods. Lets say for the purpose of this question, keep it under $1000.

98 GMC Sierra 2500HD 5.7 Vortec. More power would be nice, but in this case I'd much prefer some better fuel economy. Running conservatively only highway driving the other day I was only able to get 13.8mpg and my usual driving only gets me 12.5. I don't want to sacrifice any of the power I have now, but would like more fuel economy. Oh yeah, the truck is stock except for 265 tires as well. I do plan on putting on some type of exhaust in the future, but am unsure as of now. For this purpose, I'm very cheap, so it'd have to be quite an improvement to justify me spending $500.

Thanks for your help!

For the Duramax an exhaust set up and programmer would get ya perfect for towing and better economy. One my friends installed the exhaust himself with few hand tools in bout an hour. Gained alot of torque from the programmer.

The Vortec I would put e-fans and better ignition system.

Programmers for both... I got a tuner for my mustang and I am totally sold on them now.... I have a 99 chev and get about 17 mpg highway , I am buying scribes for myself for christmas so I will let you know what it did for me... My mustang got 30 horse and another 4 mpg so I can't wait to see what they do for my truck