Question on port placement???

[Javaman]

Help....

I am building a sonosub of about 2 cubic feet with a Hsu-type small footprint design (tall and skinny 14 inch sonotube). Using a 3 inch port, places the inside port opening close to and directly behind the driver.

Is this placement a problem??

Wayne Jaeschke on speakerbuilder.net strongly discourages this - mentions he had to install an X brace between the port and driver to correct port noise problems. But I am not finding any such dire warning from other sources. And, near as I can tell, Hsu places his ports dead center, and unless the tubes are curved inside, they likley open directly behind the driver.

A 4 inch tube would have to mounted be off center and folded 180 degrees and I assume would not have any problem.

However... wouldn't the internal ridges caused by splicing in elbows cause air turbulence and noise?

Any feedback highly appreciated!

thanks
peter