[Wbo2] Wideband O2 and turbo motors...

[David Allen]

  I'm planning to get (make or buy) a wideband AFR meter for tuning my turbo
engine.  Having no experience with these i've got a few questions.
Is it best to install the WB-O2 sensor before or after the turbo?  In other
words, should it be between the manifold and turbo; or between the turbo and
muffler?
  I've insalled a conventional narrowband O2 sensor before the turbo in the
crossover weldment.  Here, it samples blended exhaust from all 6 cylinders
just before it enters the scroll housing. Would this suffice for a WB sensor
or do I need a second, after-turbo fitting?
  Second, what should I expect to spend for a commercial wideband AFR meter,
preferrable one with a simulated narrowband output and datalogging
capability?
  Thanks in advance,
David