I'm not removing updates or features from a Windows ISO, I'm adding updates (hotfixes aka KB*******) to an ISO with RT7 (which works perfectly fine for what I need it to, except for the slowliness). But, because Microsoft has set those updates not to be integratable, an error will pop up during installation of Windows with the above mentioned updates integrated (experienced this myself). If I don't integate those 3 KB's, Windows will install just fine, and with most updates preinstalled.