Before you go and make changes to the kart, you might want to check on the rules in the area you plan to race at. Not all orgs allow the seat to be laid back. If you plan to run a KART/MARRS event, I can help you here. This series races in Ks., Ok., Ne. Around here we all run a 16 tooth front gear. We have ran both the sprint & R.R. hub and biggest difference we seen was that the R.R. hub lasted longer.