"Modifying the fuel delivery, intake and exhaust from the original certified configuration is against federal law"

Defeating or tampering with emissions control devices is against the law. However, not all intake and exhaust system modifications or replacements count as "defeating or tampering with emissions control devices".

It is perfectly legal under federal (and CA and CO) law to replace an intake or exhaust system as long as any associated emissions control devices (e.g. EGR system, O2 sensors, catalytic converter, etc.) are still connected and operational. Since my exhaust and intake systems involved no such emissions control devices, their replacement was perfectly legal.

My injectors *might* be something else...