We've been round this loop before. The garage is untreated and standing waves are uncontrolled. Therefore placement of the bass speakers will have a profound effect on the balance at different points in the room.
Technical Editor, Sound On Sound...
(But generally posting my own personal views and not necessarily those of SOS, the company or the magazine!)
In my world, things get less strange when I read the manual...
Re: What is it which makes a subwoofer "omnidirectional"?