turbo build/ mild restore

T56MaxTorq said
I'd vent to the downpipe. I don't know how you'd gain a noticeable amount of power by exiting to atmosphere. It may be easier or smoother for the gate to open since there isn't as much pressure in the atmosphere. But then you must think about O2 sensor. I'd want all my exhaust passing over the sensor, not most. They do have a unique sound vented open.

The a/f wont be effected by dumping the wastegate to the atmoshpere, unless some how oxygen goes back up the wastegate. The O2 only needs a small sample of exhaust to get its reading. If the wastegate dumped all of the exhaust out of it when open it would be a different story.