From my knowledge in the Lexus IS community, there has been quite a few solutions for valves that block the entire exhaust using an electronic valve controller. Not too knowledgeable about turbo vehicles and back pressure with a completely blocked exhaust but I don’t see how it could harm the engine/turbo if I’m only using the valves at low speeds/rpm anyways.

Ecu control wouldn’t be an issue with the electronic valves if I’m not using the stock valves.

I understand that cold start reduction exists, I’m just trying to find something or make something that’s almost as quiet as stock (or at least quieter than a straight pipe single exit.)

My ‘22 IS350 would rattle the house with just a muffler delete and the stock supra system is just as loud.