Have an 05 WRX here just failed on emissions high idle lambda 1.07. CO 0.01% and HC 12ppm. Exhaust leak before my secondary lambda sensor is the culprit. Rather than fixing my stock exhaust, I have a complete new 3" turboback system. Has anyone on here with a newage pass nct with just the up pipe cat on its own? No downpipe or centre cat?