Kenny,

Increasing the exit hole diameter will increase the power, as well as noise.
At its high price and low power gain, I would not say the Mac's is a worthy investment.

But if it is good for you, who am I to doubt it.

A tuned pipe (full length) is not suitable for a 3-D model, unless it is tuned to aid the engine at mid-RPM.

A wide range tuned silencer, like the MVVS #3248 is much more suited for this purpose, but you will have to supply the header.
I believe Mac's makes one that is suitable for the .50SX, or you can make your own.