Congrats on your BRZ! I have a 2016 Hyper Blue BRZ and installed a STi performance muffler in the past few weeks. I was under the impression that the STi muffler is an item only available through JapanParts or for the JDM from a dealer in Japan. I don't know how to post a photo on the forum (sorry, I need to look that up)
of the muffler on my car, but below is a link to the muffler I bought. I'd like to know if your muffler is the same as mine and would love to see a photo of it on your car.
https://www.japanparts.com/parts/detail/40965