I would put it before the turbo. Seems like after the turbo would be too inacurate. I could be wrong, and i agree that if there were a chance it could potentially break and ruin the turbo i would be careful too. Does anyone make an aftermarket exhaust mani that could have the bung formed right into it? Might be something to look into for best results unless cash is ah issue.
I just dont know if putting it after the turbo would be worth even having if its inaccurate.