spintech muffler

Has anyone used these http://www.spintechmufflers.com/
I have been toying with the idea of making one to fit in the engine compartment under the turbo and ouput to one or twin sidepipes with simple cherrybombs on. It should make for a high flow ane a bit quieter. Dont want to wee of the neighbours too much at 6 in the morning.
I would have to sort out the internal measurements if I go that route.
Dale