I have an '05 Sporster 155hp model with some minor modifications and am looking into an impeller for my next purchase. With the 3" intake and the exhaust mod (going to modify the waterbox and replace the whole exhaust from waterbox out) it is running at 7,600rpms. Most of the recomendations i have seen for the 4-tec n/a are the 11/19 impeller. Would this still be a good one to use or could I step up to a different pitch. All the mods in my sig will be done at some point. Looking for a little more top end and something more out of the hole.