I know signal integrity as digital design related, so if I were to write/ask about that, I'll probably use the FPGA section of the forum. If you mean signal integrity for radio/analog, maybe post in 'RF, Microwave, Ham Radio'. Each forum section has a small description, see where it fits better. Or, post in 'Projects, Designs, and Technical Stuff', which is a less specific section.
Anyways, one can move own topics from one section to another, so if you change your mind, you can move the entire thread later. There is a move topic button at the very bottom of the webpage, and a dropdown menu to choose where you want to move the topic.
Whichever option you choose, don't open the same topic in multiple places. Duplicates are not allowed on EEVblog.