Where to start. Easiest way is to plug tech2 in and activate them remotely.
Failing that... The front multi ram sits in the alloy section of the air inlet. Between Maf and throttle. The inlet, or bagpipes, are the first thing that has to be removed to acess the cam belt etc, and usually the last thing to be neglected on re fitting.
Check the electrical plug connector is seated correctly. That the two vac pipes are routed to the vac reservoir. If so and still no joy there's a one way valve in the vac tank that may have failed. Replace vac tank from a breaker here.
Rear is similar on the back of plenum, except the vac tank for that is behind the pollen filter housing under the scuttle. This one though, I'm fairly sure affects top end rev range. Hence suspect the front multi ram in your case.
Hth