Cargraphic's is not only muffler, but also sport cats, that's were the power gain is coming from.
Quality is very high, but I'd look into the Tubis also.
First level is basically same as stock, Super sound (3rd version) is not TUV approved, but is really wonderful albeit pretty loud...(makes me smile to say that if I compare it to my Modena, I guess it's all relative...)