Pretty sure I need to drop my CR. I'ms till at 10.1 with stock LS1 ported heads. I considered the 317's but I was told they only flowed 5cfm better than a stock ls1 head. I wasnted something I could benefit from a lower compression and just an overall better flowing head. I will aslo be running anywhere from 10-15 psi. Thanks in advance.

 

You can run a 317 head, and possibly a thicker head gasket and be okay.

 

You might be OK at 10:1 if you run methanol.

 

well a stock ls1 head flows like 227cfm at 600
the stock 317s flow 24x at 600

the 317s would drop you down closer to 9,10cr
I have a set thats been hand ported bare casyings i might sell cheap

 

http://www.smokemup.com/tech/ls1.php

here are the flow #s the 317s are really popular on fi setups

 

Get the 317's, you can get them used for cheap and as far as I know, they have LS6 ports with larger combustion chambers, which should drop the CR by almost a full point compared to stock LS1 heads.