I have been using a Walker 17783 on our '88 waterboxer for over a year.  It is accompanied by a 2.25" catalyst from a 16V Scirocco and 2.25" tubing as a tailpipe.  Yes, the longest tailpipe possible is important to keep the noise level down.  Ours is growly at idle, and makes a vocal hum at speed.  I like the sound that engines make and to me it's music.  I have had cars in the past with obnoxiously loud performance exhausts.  The Walker Super Turbo is much better behaved.

Regarding performance, our '88 also has a Jacobs "Omni Pak" ignition amplifier.  Our local VW wrench has asked several times after servicing the Vanagon "are you sure that's all that you did to the engine?"
When given to pushing a bit she'll pass traffic up significant hills at 80 mph.  

The "pea shooter" stock exhaust is begging to be changed.  Go ahead!

Gary

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