Light weight helps in stock. Anything other then that I think its ok to go heavier. In stock with my light B4 1507g compared to my Dad's 22 with a full stick and aluminum parts 1670g acceleration is very noticeable. My buggy has more rip for sure. When I ran an 8.5 in my B4 I could not tell the difference from extra weight shorty vs full stick as far as acceleration and power.