To avoid as much drone as possible. Look for resonated everything. I have FI Res TP and the APEX'i RS Evolution Extreme with 18" Res on them. It is just loud enough when you step on it but there is no drone at highway speeds unless you are around 2k RPM in 6th. There is still the smell of gas because of the TP but other than that I enjoy it. Let me know if you want a clip of the sound... mind you the exhaust itself is fairly expensive for not including a y-pipe... BUT its JDM
