Average size is 6". My truck is still basically stock. Let's do a little math using my current rig... XOC style!

Mod - E-Penis Size
Stock Xterra - 6"
Round Headlights - -2" for not having square headlights
BFG AT/KO's - +2" for tires
Having 32"x10.5" - -1" for not having 32"x11.5"
Steering Stabalizer - +.5"
Calmini Idler Arm Brace - +.5"
Shrockworks Sliders - +2"
Not having them installed yet - -1"

According to my calculations I have a 7" E-Penis. Once I get my lift and upgraded steering I'll be adding a few more inches to it!

Oh yeah, as long as I don't roll my truck I will maintain my E-Penis size. If I roll it or get into an accident then I automatically goto a default 4 incher.