So much bickering. I'm going to pull the trigger on the gytr cam and head you can google the specs under 14 wr450 gytr head cam upgrade. I don't know anything about duration or anything else. All I know is kick but vs kick a@@. I also have ridden 2002 cr250. 2010kx450, 2012 kx450. And just want flat out more balls out of my 14 wr450. So I will post back if there is a huge difference or not.