well ur car being heated up COULD mess them up. im not sure. do it again with it warmed up
or ur piston rings r leaking or ur valves r leaking. u need to do a wet compression test to see if it is either rings or valves. im not sure wat normal compression is for the gsr but it may be 220...the LS is 180...
for a wet compression test just put 2 drops of oil in the cylinder, let it soak for a couple min then do the same thing as the dry test. err actually wait till u do the dry test again properly