I have never hear them before. the muffler I am going to do is a flowtech afterburner. it is queit for normal driving but when you put your foot in it is when it cames alive. 3'' piping to the Y and then 2.5 all the way out with the tips off of the grand prix store that are staggered. i had spend months on youtube trying to find a gxp with a different catback then magnaflow or straight piped. if you have some more questions just let me know.