I need to change out the silencer on my son's KX 65. We do a lot of hare scrambles but they never check the pipes. Does anyone know if there is any significant difference in the Turbine Core 2 vs the Power Core 2 as far as performance? The bike has an FMF Factory pipe. Thanks!

I don't know about power but the Turbine Core has a spark arrestor which around here is required for off road racing and trail riding. I would guess the Power Core would be the one for closed course racing and probably have a bit more power.

The Power Core will rev higher and more freely, but the Turbine Core will have better torque, and is much quieter.

As far as KDX's go at least, I have a TC2 and my buddy has a Powercore2. Same bikes, different chambers though as well. He has the Gnarly woods, I have the Gnarly desert. My bike is louder, and has WAY more top end than his, however I attribute that more to the chamber than the silencer. It seems like my TC2 flows a little better, or at least looks like it. The opening in the end of mine is about 1/2" bigger than the powercore.