i have the lq4 with the 317 heads on it. i am changing them either with the ls6 stg 2.5 64cc or the 5.3 heads stg 2.5 59cc from TSP. i am wondering what the c/r will be. if i use the ls6 and if i use the 5.3 ones.

 

The stock CR of the LQ4 is 9.41:1. If you bolt on a set of un-milled 243's the CR should be right around 10:1. If you bolt on the 5.3's, I "think" you should around 10.5:1. But you could always mill the 243's to get you to your desired CR. I'd shoot for right around 11.0:1. That's still pump gas friendly.