It wont look bad. By checking your plug i mean a plug chop. After you put on the silencer(if you do) then ride it through all the gears then take out your plug and check the color. to light is lean and to dark it to rich. It should be a tanish brown color. I think there is a dyi thread for this.
Depends on the silencer. Right now ive got my stock pipe with my dg silencer on my 01. It doesnt fit perfectly but it works. I think the fmf powercore 2 silencers will work to, they look the same as the dg side by side.