2006 silverado going from a 78mm tb to a gto 90mm tb I know I have to adjust the etc area scalar. I have downloaded the xls file, it has two tabs, a tb change size area ratio and a effective area per 1%. Im grasping im going from a certain area to a larger on. what is the formula i need to use to put into the etc scalar the correct number? and how do i use the spreadsheet? im assuming theyre all pretty much the same...