having no muffler does gain power. I know this cause that's how I always roll.
this is also basically the same thing as the kazuma. I dyno the same as the TRD
exhaust. (cept it was free to do lol)
TPR's exhaust dyno was much better then mine. and it's a lot more quiet then the way I have it now.
the theory -
the theory he used when creating his exhaust is simple. keep the gas hot and the velocity up.
also it's really light so thats a bonus too.