Web site that does and ACT - SAT comparison

This one of many links that compares the ACT and SAT test scores. If I read it correctly the writing portion of the tests is not included. I believe the writing portion on the SAT has a bigger impact on the final score than it does on the ACT. I may not be accurate on this but this is what it seems. The writing on the ACT does not really seem to change the final score. I say this because my sons English and writing scores varied by 30% and his final ACT score remained the same.

http://www.eguidancecounselor.com/act_sat_comparison.htm#SCALE COMPARISONS