I'm on your side not to remove the manifold but the haynes manual says to remove the intake manifold to access knock sensor. And when you do, change the manifold gasket and be careful when you pry the injectors out.

I also found some posting here while doing some search re knock sensors that they try just to remove the cooling fan to have a better space to access the sensors. I guess you have to choose either one is the least complicated task but weigh on what the book says. Goodluck.

chrisq