Thrashers are known for their idle quality. However, it's recommended that you don't use a catalytic converter when running a Thrasher. Don't know if this matters to you or not. Otherwise, like tim87tr said, there's alot of opinions on this. There are also alot of good chip burners out there too that can make you a custom chip. The Thrashers seem to be the cheapest at $25 each. The going price from the rest of the lot seem to be about $75 each.