Stefan.........I probably wouldn't bother with the taper of the needle. Just run it rich on the bottom.........Tight clutch...........and tune the HSN for top end performance. Your lean bogging will go away. I spent a whole afternoon figuring that out. I believe my low speed needle is 8 turns out. I know you will be tempted to lean on the lsn as all engine tuners want to......... but resist the temptation........It will sound fat........and it wil be......but on the track it will be fine. The other big plus..............is when the others are struggling to make mileage............you won't!