Bought my 10 yr old son a 2014 Kona Stinky 24 to ride downhill. The spring on the shock is a 300 x 2.0 and IMO way too much for a 70 lb rider. What spring do you think would be the best option for my 80 lb son? I was thinking a 150-200 x2.0? Who should I contact to buy a lighter rated spring? Thanks in advance!