I agree with snackem. My next X2 build, I am gonna cut glass, and the OEM exhaust is moving forward, adjacent to the waterbox. This (in my opinion) will enable tubbies and also enable the exhaust a straight shot out of the waterbox.
With the exhaust farther forward, in a tailstand the exhaust stream will be further away from your face. In subs and nose stabs, I figure the exhaust outlet will be underwater less time because it will be out of the water sooner.
On the noise issue, I believe the waterbox has done it's job, and a straight shot out will not be any noiser than the OEM location.
Prof