well whats the price difference from your sources between oem and spi? this is a pretty critical part, and if it lets go you are sure to cause damage. i always look at the money i am going to save vs the money its going to cost me to fix if it goes down due to that part failing. usually its not worth it. i have the original pistons in my red head and it has 21,000 km on it. so i say if its proven and works, why change it? go oem.