I was looking at replacing the muffler on my 2021 Silverado RST with the 5.3l and single exhaust. The mufflers that show up in a search are 2.5" and 3" with different searches contradicting each other on the correct size. Even trying to get a muffler from online has both sizes coming up as NOT fitting my truck. I decided to measure the size on my truck to settle the matter, and surprise, surprise, it's 2.75" and all the sites say this size won't fit my truck. To make matters worse, I would need a 2.75" offset in, center out muffler, and the only ones I can find are super expensive. I looked at a muffler delete pipe, and they say that those are 3" diameter.