I currently drive a DSM and this is a very popular choice for us, we only use one, Supras only use one. I believe the stock piping on that is 2.25" and you can usually pick them up for about 100-150 a piece. Supras have proven them 'good' up to ~500hp (just what I've heard, wether this is wheel or motor, idk, but I have a buddy that put down 40xhp at the wheels on stock turbos, stock sidemount, pretty typical limit on thoes).

Just wondering if anyone's looked into these, thinking about geting an s4 but I'm cheap (does that make any sense)? I just think they are very cool, quick, nice cars. Just the aftermarket is way expensive, especially if you can make everything you need... like I said, I'm a DSM owner (read as chepa ass).