Guys, these things are a rip. Search the forums and you will find several discussions. The theories they present as to why their mufflers work violate two of the laws of thermodynamics. And, if they are so good, why don't they compare themselves to other mufflers? Note that they only compare themselves to stock mufflers - if you ask for comparisons to other aftermarket mufflers they will tell you that the data is not available. Save your money and buy a better muffler for less money (Magnaflow/Flowmaster/Borla'etc...).