Today my new AFR 185′s came in the mail (AFR part# 1389). These are the heads with the upgraded exhaust ports for nitrous/boost applications. They were a little pricey because I decided to get the valve spring and valve upgrade (for higher rpm’s and higher temps). The upgraded port option basically bores out more material on the exhaust ports
along with smoothing them out for increased airflow, which is what boost and nitrous applications like to have (on the exhaust side). In the picture below (right) you can see towards the top of the exhaust port the part that looks polished. This is where the material was removed.

These 100% CNC ported heads come standard with 2.02″ intake valves and 1.60″ exhaust valves and flow 277 CFM intake and 191 CFM exhaust at max lift.┬áMy Ford F303 cam only requires .512″ lift which should flow pretty close to the heads max at .600″. For more information on these heads visit www.airflowresearch.com.