Considering I know fark all about exhaust systems..... I would think with a turbo system, since the turbo is in the way of the exhaust flow, just bigger is better.
The big thing seems to be the length of the dump pipe for excess boost. The further distance down the exhaust this joins in the better since it is a massive sudden rush of super hot gas that disturbs any existing even flows.
but thats about all i know. the rest is all black witchcraft to me.