Myself, I make my machine take as much of the abuse so I don't have to. I'm not sure what you mean by lowering the front end?
As far as wheel spacers, don't do it if you are going to run a race through the woods. There will be many instances where you can JUST SQUEEZE through. Add some spacers and you will have to two wheel through certain parts of a trail.
Equipment essential for harescramble racing (other than the obvious personal safety gear):
Tires and suspension. That's it. From there you can keep adding stuff.
Armor, steerring stabilizer, axle, wheels,...ect...
Things you have to have for the only harescramble series in the state of Florida(FTR):
Kill switch tether cord. (*we have seen riderless quads many times! LOL!*)
96 decible or less sound level. This means some stock systems may have trouble passing if the packing isn't fresh. My YFZ with a stock system read 92 dB. I will say this; every loose nut and bolt will add noise and increase the dB level. So your pipe might just be okay, but your armor bolts or whatever, will make the sound level higher and your pipe will get the blame
I have seen the best riders with qa stock pipe kick the crap out of others who are piped.
After an hour of giving it all you got, you still have another hour. You are tired, if not exhausted. There is NO exhaust PIPE IN THE WORLD that will help you now.
Suspension is a must. Dialed in, that is.