Dear club members! Have a Mustang 67 with straight 6 and 200 cui ie. standard engine, 3 speed manual. Planning to upgrade the standard muffler to one with more muscle car sound, more of deep and low frequencies. It is always a consideration of how much it should be heard inside, preferably moderately but not too little either Looked most at Flowmaster 40, 2.25 ". Do any of you have the same or other that you are very happy with?