I've been looking at them too. They are normally anywhere from $250 for the 63 up to $350 for the 77 that fits the 3.7 so $100 is a really good deal if its in good condition. I've read that the horsepower gains aren't "provable" but that it gives a little more power, helps the engine breath better, and gives it a nice sound. If you decide to get it take some pics after the install so I can see what mine would look like.