So my 04 wrx starting knocking bad a few weeks ago. Im planning on buying a new oem ej20 shortblock. My question is should i do anything with the turbo? It has 90k miles on it, and the last thing i want is for the turbo to blow up and takeout the new block with it. How reliable are these turbos? I autocross the car on occasion,and mainly want it to be reliable. Also what should be done to my heads before installing on a new block?