I've been using MEP since the 2008 version. With the 2010 version, Autodesk decided to include automatic unions. Anytime you join two sections of pipe a union/couplilng is inserted. Also, anytime you extend piping from a plumbing fixture a union/coupling is inserted. This is a serious pain. There is no reason for me to show unions at these locations. I've gone through the AutoCad MEP 2010 manual and it seems like this is built into the system with no setting to turn off. The only way I've found to get around it is by using the Standard routing preference. Please don't include this setting in MEP 2011.