I put mine in the manifolds... for the driver side I actually tapped and threaded the plug in the 300 degree EGR elim. kit. Easy to do, and no chance of screwing up the manifold. Tapped the passenger side manifold itself in roughly the same place. I was nervous about the possibility of the probe coming apart so I got inconel probes. The instructions will usually tell you to put the probe in the middle of the exhaust stream. I have seen other posts here saying if you want to reduce the chance of your probe coming apart then instead of doing that, only protrude the tip into the manifold, but honestly I don't know the truth to this or how that would affect accuracy. my $0.02
