Yeah no real increase BUT they flow way better, old 146 tune it peaked at 5k and then dropped dramatically. now it peaks 153 and holds peak power all the way and beyond 7k so effectively theres 2 k rpms worrh of peak horsepower on tap, dave rekons it pulled like a steam train in 3rd now and will go happily to 8k rpm. Still more work to do on them but i think Dave is calling it a day with those heads and doing the superflo's over the winter.
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