I want to hyper a N6 does the f2 rasp bar look like a M rasp bar? Got a bar from junk yard gave them 71142277, bar I got looks like our bar off of an M, picture on this site looks different. To create Hi-Lo can I grind teeth off of forward, reverse bars to get same effect or is this wise? I have helicals where I should mount the f2 bars so how many helicals should I remove? Adding helicals and double stacking over concave is this step necessary? Lot of questions so thanks