I'm not familiar with either one and it's about time to make a decision as to which one to use. I have no hands on experience with either one so there will be a learning curve one way or another. Most of the 275 guys are using the 7531 box that I have seen but I have heard that the power grid is supposed to be the replacement or next evolution of the 7531. So what do you guys think? They are both about the same price, have no experience with either, and I need an ignition that allows me to pull timing while on nitrous. What would you choose in my situation? As usual thanks for your replies!