For thos eof us who have been doing this a long time, there can be a big different depending on your setup. A 20* difference is large. Another member who will go nameless since he hasnt posted not only had a noticable difference in air intake temp but it also affected his EGT temps. Now since we dont have thermocouples in our cylinders I cant tell you the cylinder temp is lower but if 1+1=2 even a Mechanical Engineer as wise as yourself can make the assumption the cylinder temps were lower.

Now this is very setup dependant. With a Log manifold the Cold air intke may or may not cause the same effect but for those of us with custom equal lenght manifolds, there is a sizeable value to having the filter in the bumper.