Bpape, do you mean that i need at least 4" thick for the triangle trap?
Currently, i have 2 4" thick traps in the corners behind the speakers and 2 6" thick traps in the corners behind my seat. I could not put another panel on top of the current ones due to several factors. That's why i'm thinking of DIYing the corner like the one i see echo buster.
Also, i look at GIK website, and the triangle trap is interesting. Is it solid inside the trap?
thanks.