Got a stock 2002 KDX-200. Getting ready to buy an aftermarket pipe. 99.9% sure that I will go with a Pro-Circuit. Anyone used one on this bike and how much does it affect low end power-Think it improves mid to upper range really good but at what cost to bottom is the question and if this is true what can I do to remedy this. Plan on running 13/50 sprockets. What type of sprockets and chain anyone(Renthal, Sidewinder-pricey!) Also, springs for my weight at 155 pounds with no gear-Race-Tech recommends 38' for me for front- does this seem right? And rear, looks like 4.8 rear spring for me because I cant seem to get sag right for my light butt. Would like to go racing this spring and want to get bike's handling as good as possible. Really enjoy this bike alot, have rode it stock for a year now and ready to get serious with it. Owned original 1980 kdx-175 (brand spanking new at the time and absolutly loved it too). Ready to do lots of other good things with this bike and any info from anyone will be helpful and thanks for the time. Also everyone have a Merry Christmas!