No worries there on the SRM - there is a lot of acronyms to learn
Yes tunnel and under ground parking hunting is a fun new game with the exhaust system. The Stillen sounds fantastic and the HFC gives it more growl. Tame when the throttle is light and it sounds fantastic when you romp on it. Almost an exotic note....
Grounding kit - the engine is mostly isolated from the chasis for obvious reasons. This doesn't make it the best path for electricity and in particular the sensors on the engine so the grounding kit improves the grounding path for those sensors by adding additional grounding points from the engine to the chasis. Helps the sensors to send the best/cleanest/most accurate info to the ECU which in theory will optimize the power/efficiencey of the engine.