Top of the downpipe by the shock tower. I'll see if I can find a pix. The only thing that sux, is the DP has to be taken off to tig the bung.
Some guys will put it on the elbow, some will do it on the test pipe.
For WOT it wont matter where its located. The closer to the turbo the better it is for drivability on an aftermarket computer.
HTH