the only benefit I see is... um... none. your dumping hot exhaust gas, instead of using that energy to help pull exhaust through the turbo (exhaust scavaging).
and the reasoning you gave sounds wrong. how can this 'mod' allow more flow? the flapper (internal waste gate) is still the same size. you're just dumping it into atmosphere. (aka, a noise mod). and I certainly don't understand how it can prevent boost creep.
interesting idea regardless, if you're into the whole 'mod for any reason except a real purpose' crowd. (affectionately known as "ricers").