Can't comment on the Street Pro or Violator but I had Flowmaster 40s on mine, couldn't hear myself think. So loud my wife wouldn't ride in the car with me. For me they are too loud. I changed to Dynomax flow-through, a lot quieter.Still a bit loud but has a good throaty sound not just noise like the Flowmasters and really bark when I tromp on it. Could have gone for quieter but wanted some performance as well. Look in Jim Hand"s book, he tested a bunch for flow, decibel rating and performance on the track.
