I have just finished breaking in my stock bikeberry 66 cc kit and have around $50-$60 I could put into it. I mostly use it for short trips and I wouldn't mind having a higher top speed, I'm ok with it's current sound level, wouldn't mind it being quieter. Engine seems to get a really good vibration/rythm that has more power, but only when giving it gas going uphill. I'm pretty big 325#'s so I don't want to further abuse the bike with a smaller gear. I was thinking of either carb, exhaust, or cylinder head upgrade. CCI seems to be a bit out of my range. Thoughts?