First I thank your gearing is way too high for the pede and a 17 turn. Something more like 15 to 16 t pinion size would be more like it. With your gearing and higher MAH packs (longer run times) your going to run into heat problems.
You will see a huge run time increase over your 1500 packs with a nice new NIMH pack with a high MAH.
A few place's to find alot of good info on the Stampede. I love the truck so feel free to ask away. I will help with what I can..... These 3 site contain tons on top of tons of info on the Stampede.
Gearing info.
http://stampedeproject.com/How_to_Gear_you_Rig.html
http://www.ultimaterc.com/forums/forumdisplay.php?f=30
http://stampedeproject.com/Traxxas_S...de%20Exclusive
http://www.misbehavin-rc.com/pit-lane/es-pit-lane.asp