I have a 98 yz400. I am thinking of a new pipe for better bottom end, or header. The selection is very limited with this being such an old bike. Heres what I have found. FMF, Pro Circuit, DR.D, and suppertrap all have a pipe. I was looking for some opinions on which one would possibly be better for low end and if I should look at either the silencer or the header for the best gains or should I look else where. Thanks guys.