Oh... I almost forgot!
I'll promised you my spartan graphs... Here they are

. It's just a sweeped sine wave tone recorded about 1/3 in from the front wall in the center with a sm57 but you could clearly see the difference that only 4 traps do. The upper graph is the untreated room and the lower is the room with four traps (two in each front corner).
I've allready bought more material so I can make 4 traps more. Now I just need some time doing them!
/Cojo
I have tried loading up this image at least 20 times, I don't know why it doesn't show? Can somebody see it?