The long awaited SpeedCircuit Heads for the 4B11 Evo X are now available! All SpeedCircuit heads are completely stripped down and rebuilt, including new parts where necessary. There are two stages of heads available.

Stage 1 includes:
-Special five-angle valve job
-Bowl work to blend the stock machine cuts into a larger bowl
-Resurface (if needed)
-Disassemble/clean/reassemble
-Sandblast clean
-Valve lash set
-Pressure tested to ensure no leaks
Stage 2 includes all of the above, as well as -Completely ported and knife-edged intake ports -Completely ported and knife-edged exhaust ports -The extra porting and knife edging results in a larger port that is more consistent than the stock port, resulting in smoother power and better airflow. NOTE: This product is a SERVICE ONLY and requires your head to be sent in.