i check the c-speedracing.com calculator and it says compression will be 12.1 and i use the http://www.bojangs.com calculator and put me around 12.3... i was wonderinf anhyone actually had a better reading of what the compression is using a stock gsr head wihta pretty much stock b18c1 bottom end (ctr piston in it)

 

both have mixed but close readings because everything is different. like what headgasket you are using as well as the vavletrain.