With the engine running look just under the TB for a small connecting rod, rev the engine up quickly and you will see the rod move. This is the secondaries opening from the IRMC box on the front of the engine.
Just as a footnote though, if i rev mine up slowly the 2ndarys will not kick in until 5000rpm or above, if its done quickly then they open pretty much Ok. I also figure that there is a heat build up issue in the IRMC if you have an older car. Has anyone moved this box of tricks to elsewhere in the engine bay to combat heat build up issues?