I realise there's been heaps posted on this subject. However, my bike runs best (admittedly subjectively) with quite different jetting from the tacitly agreed standard on this forum. Using a Barrett straight through muffler (quieter thean stock - how come?) and standard headers, airbox opened up with 5 x 32mm holes and stock plug (I have used the iridium plugs and reckon they are a waste of money - IMO), I run a 175 main, stock needle on #3 groove, and a 42 pilot approx 2 turns out on the screw. Everything else is stock. The bike goes better than ever. I have tried a 45 pilot, JD red and blue needles from an 05 510 as recommended on this forum, and mains up to 185. My Husky runs sweet, fast and smooth even on long downhill over-runs on the hard-top with no lurching, bogging or any other problems I can detect. It pulls noticeably better on my uphill test road with the above settings (The Mt Barker Road for those who know it).