but had a very deep tone that made my Z sound more like a V8. Resonated considerably @ 25k rpm. Great quality of constuction & welds. I have since replaced the Stillen mufflers but retained the double y pipe. Tone changed slightly but still resonates @ same rpm so I assume this is due to the Y pipe considering others I know with same muffs & using the H pipe are quiet by comparrison & don't experience the resonance I do. Of course your turbos & lower compression when not under boost tend to quiet things down a bit as well.