All to which is subjective in manner. Many states are more stringent on exhaust modification laws and to pass SMOG. For 2001-2006 BMW M3 3.2L L6 (E46 Fourth Generation). Material: T304 Stainless Steel.
I wold recommend this product as to the price and the quality, but the hardware and fitment leave a little bit to be desired. The hardware they sent was too short to be used with the headers that are stock on the car. I had to reuse the old hardware which is really no bi deal, but if you broke one of the bolts taking them off, then you would be SOL. Also the first section was a bit too far over in the tunnel that runs toward the rear, so I had to hold them in position with a piece of 2 X 4 until I got all other sections bolted up and in position. The quality of the clamps is very good and they hold well. The way they all slide together is easy to do as well. basically a nice product.