I have a vision 8 ball 2011 6500 miles on her the last 2 weeks she has started to make a rattling noise when first started its sounds like a can of nails when giving her throttle last till she gets heated up. turn it off for 15 mins still hot she makes the noise. also backfiring way to much when gearing down. this start about the same time. way too noisy at first. havn't notced any lose of power. or smoke coming out of pipes. this ain't normal right.