Dumping waste gate exhaust and other questions

[Gerard]

> Performance-wise routing the wastegate gasses through it's own exhaust (including muffler)
> will be "best". Corky Bell mentions that the turbulence caused by wastegate gasses coming
> into the exhaust pipe after the turbo has detrimental effects on the flow of exhaust. But
> since all the exhaust needs to go through the catalytic converter, and also preferably
> exposed to an O2 sensor, I'd keep it routed into the main pipe like Audi did it from the
> factory.

Which reminds me to ask the following question: where's the best
location for the O2 sensor, should it go into the plug hole at the
collector leading into the turbo or should it go into the downpipe just
behind where the wastegate connects up to it? My 200 did not come with
an O2 sensor so I have to have one put in, but where's the best location
for the most accurate readings?

G.