Has anyone installed these on a 790 Bonneville with stage 1 mods? (Airbox elimination kit, preditor exhaust, and jetting ) If so, what improvement, if any, did you notice? The stage 1 mods were well worth the money with the improvement in midrange performance. British Customs says these manifolds will improve the bottom end. I have no reason to doubt them, but $200 is $200 and I would like to hear from anyone who has made this mod to see if it is money well spent.