Yes, because it deletes the catalytic converter. You can run STX with a header and high flow cat, though. 14.10(E) if you want to look it up.
Sedan Revolution #103
focus in storage. hit a rock with the oil filter and locked it up.
gotta sort out a 351w 4 door fox first, then the focus gets a 2.5
commuting with a v6 5 speed mazda 6 wagon.