I have used them in the past and often said these are the quitest mufflers I have ever used.
I now use something quiter. Hooker Aero Chambers. There on my 400. While a stock low compresio0n engine, they are 2-1/2 inchs in diameter. The exhaust is Headman Elietes down to a H pipe.
All piping is 2-1/2.
Now, at any speed except from idle to 1500, give or take, I can talk to anyone in the car at anytime, with or without the stero on, which I can here at very low volumes.
Thye only * I give it is that you want a 3 inch tube. Now theres a difference to think about that I'm not to familur on.