Pass. Exhaust Mani crack = How much power loss

[WKF]

Ive always heard if you have a exhaust leak PRE turbine housing / o2 that your leaving power on the table..... Anyone know just how much a leak like this one is capable fooling the computer? This one is on my passenger side & it looks as if the o2 is pretty open to atmosphere.
I have a nice replacement ready to go on, just curious if anyone has a good educated guess on just how much a crack like this can put off my XFI.

 

[TurboDave]

Any pre turbo exhaust leak is going to cause false readings by the O2 sensor, and will drive the BLM's abnormally high causing and overly rich condition.

 

[pacecarta]

he doesnt have blms ...xfi
wot not much diff in power or o2 readings as the pipe is under pressure
but for et loss on the low end
leak would cause you to have slow spoolup just due to the leak of pressure to drive the turbo (acts like an open wastegate),
also would give slower spool and worse mileage due to air coming in if running correcting (based on an AF ) as the low end would be richer than actual target

 

[turbo nasty]

System is designed for no leaks.

 

[bison]

It wont hurt power one bit. A lot of guys dump their wastegates to ambient and its a big pre-sensor leak and does nothing. It will likely screw up the cruising and idling a/f but thats about it