I recently had an issue with the coolant over flow reservoir becoming pressurized and shooting coolant out the cap. After lots of testing, trouble shooting, etc it ended up being the lower radiator hose collapsing. Theory is that the 17% ATI OD damper along with the Magnuson supercharger causes it. I called a buddy with the EXACT same setup as I have and his is collapsing the lower hose as well and now I've confirmed it with three other folks with this setup. Something to be aware of. Over time I think the hose becomes weaker and weaker from expanding and collapsing until it finally collapses flat which backs coolant up in to the over flow bottle.
Now, to get to this conclusion I completely tore the top end of the motor down to check head gaskets, blocked water ports, etc. Live and learn, but good experience. A $5 galvanized steel spring in the lower hose solved the problem as the hose does not have a spring in it from the factory.
Here's a little time lapse video I did of me reassembling the motor. I thought you guys might enjoy it.
4 hours of work down to 1 minute.