Is just milling the head a good improvement or does rechambering make a big difference? I can only run pump gas. I have a stock ported motor im running with an fmf exhaust and silencer. V force4 reeds and open airbox. Im currently rebuilding the top end and my local shop does milling but not rechambering. If i wanted to rechamber i would have to send the head and wait weeks before i can finish the build. Is it worth the wait?