thankyou turborg:"
ill be experimenting with an 18rc head b 4 i start hogging into the 18rg unless i can find a stuffed rg head that i can cut a cross section into and experiment with that. We have got 2 superflow benches were i work so i can test all that. Depending on what the flow bench figures show i may need to enlargen the exhaust aswell. on a NA engine i think(enphasis on think) the exhaust air flow has to be around 75 percent of i intake airflow.