Don't know where to get some decent 8-cell packs. Of all the packs I have ran only the 6-cells fit in the stock battery tray. I run 7-cell packs and have lots of speed, running either the Mamba Max 5700 or Trinitys Speed Gem/Pro Amber 13t & 17t w/7-cell. Either set-up has plenty of power.(Brushless almost uncontollable) I don't have much experiance with motors other than Trinity, the two I have are GREAT!!! Lots of run time before brushes need changed. I went with the FLM Ext.Chassis w/Ext.Arms. Not sure how wide ya want to go, but this FLM stuff is TOUGH!! And the Ext.Arms make it quite stable, even with the brushless. As for gearing, Tower Hobbies sells a "pack" of gears. I think they are 5 packs in either odd or even teeth. Ok gears until you find a set-up you like. Just remember to keep an eye on your motor/esc temps! II don't know much about the new Stampede, but switching to 5X11 bearings helps the speed and run time. You'll have to get different carriers, RPM makes some good ones. I hope this helps!)