muffler flow numbers comparison

All I know about mufflers is, if your using Flowmasters for a street car, I would use 50 series and for a race type car use 40 series. Years ago I had a 71 Chevy Camaro with a stock 350 and headers and had a muffler shop do my exhaust and they put 40 series mufflers on it and it was the loudest car that I heard even compared to some uncorked race cars. The 50 series are a lot quieter and probably won't notice a difference at the track. Just from my past experience. Now I have TTI headers with 3" exhaust and Dynomax mufflers on my Dart and I think it is pretty loud. Stock hyd roller cam in a 380 hp crate motornow.