I am a bit puzzled as to why the hose diameter coming out of my Volvo TMD22 turbo diesel is 3.5" to the water lock (about 3 feet). The hose exiting the lock to the exhaust exit (8' or so) is 3". Is this done on purpose for back pressure purposes, or have I uncovered a bizarre cost savings measure by the manufacturer? Is it something I should be concerned with?