Follow-up ultrasounds is going to be executed often once the TIPS process to ensure that it stays open and functions appropriately. Not to my knowledge. I believe The piece that you're pointing to is an additional O2 sensor port for an autotuner or a little something of that sort http://beaunjmcs.getblogs.net/13393277/the-2-minute-rule-for-bmw-m2-competion-armytrix-exhaust-is-better-than-akrapovic-and-remus