Jkphoto is right on - you MUST find the proper positioning for your speakers, THEN have the subwoofers tuned to the room by your dealer. Take the spikes off, unplug the subwoofers, then use the "thirds" measurements in the manual to do rough positioning. Move the speakers around and play music you are familiar with until you find the spot in your room where the "magic" occurs. Do not be afraid to move them way out into the room. Do not be afraid to try rotating your room - if the speakers are on the short wall, put them on the long wall, or vice versa.
Eventually you'll find the spot where the speakers sound the best. You'll know it immediately when you hear it. Put the spikes back on, put them in position (mark or write down the positions for future reference) and plug the subs back in. Then have your dealer tune the subwoofers to the room.
It may sound like a lot of work, but it's WORTH IT.