Alex, I burned a piston at the number 7 cylinder. I took it to the engine builder I am using now and he said this was a common problem with the LS7. He put on aftermarket fuel rail and rerouted the fuel lines. It made sense what he explained to me, the fuel rail comes in and Y's, the back cylinder will not get the same pressure as the rest of the cylinders since it is so far away from the Y and all the rest of the injectors are taking the fuel first, so when the pressure drops due to the high fuel consumption when you are letting it eat, then the back fuel injector is loosing pressure causing it to run lean. He routed the fuel lines into the end of the fuel rail went down one side, crossed over to the other fuel rail on the same end of the motor then down the other fuel rail. He put the regulator after this. This way the fuel runs into the motor and is regulated after it goes through the fuel rails. I don't know if the LS3 fuel rail is the same but it has worked for me for the change. You can see the pictures of this on my build thread. I think it gets more consistent fuel pressure to all the cylinders now.