MegaCrash, It all dependes on how much power you want. I may not have gone farthur than the Pipe, Clutching, Roller Clutch, Air Box Mod, Weisco, V-Force II's if I had not been riding with faster quads. Just the pipe and matching clutching was amazing...but power is addictive as someone told me a year ago on these forums! I have not tested my new found power yet (Porting, Lightened Flywheel, 12:1 Cool Head and 39mm Carb)but will let you guys know the difference once she's been tested.

As for the nerfs... you have to cut off existing floorboard supports and weld on the nerfs and footpegs. Many hours of set-up and fitting. Only an hour or so of welding. Piece of cake...

 

I'm another one with HPD components on my quad. Along with the Delta 2 reeds, add a reed spacer to build a little more mid range.
A word of warning though, when you start making a bunch of horsepower with a 400, the stock oil injection doesn't supply enough lubericant to the moving parts. A little pre-mixed oil in the fuel will help keep the stock piston alive.