Hey Guys i'm pretty new to the 4x4 world. I was wondering if anybody had any suggestions as to how to add more power and torque to my 1999 k3500 crew cab with a 5.7L v8 (350). I just had a 6" susp. lift installed with 35" dick cepek FC-II's on 16" american racing baja's. Any suggestions???  

This one is REAL easy and obvious too yet many seem to miss it. Your "problem" is classic. You need some new deeper axle gears. No tune or add on is going to fix this and anyone that tells you otherwise is blowing smoke at you. Simply physics here. You raised the effective final drive ratio a lot here with bigger tires and it take more power to move it and less is available to do it with because engine is now turning slower at same ground speed and has less power available at that speed too! (HP is basically torque x RPM) A set of 4.88 gears would wake it right back up and feel like you had a engine transplant. Do not let the number scare you. With 4.88 and 35's you will only be turning  a bit under 2300 RPM at 65 in OD which is about right (though 5.13's would not hurt if you plan to tow with it or carry a lot of weight too) Your Vortec 350 does not really start to wake up and do its best until about 2500 RPM or so anyway so it is a good match. (I know the engine well as I have one in a 2000 K3500 std cab SRW) That is a strong motor with right gears behind it.