My thoughts on the 2.4 inlet manifold now over 2 years on is that its a waste of time and money. I only know of a few members that have had any significant gain and its not been in the torque area. Vocky's vx220 was extensively modified beyond what mine was at the time. His included oversize valves and probably better porting than mine with a 4-2-1 manifold along with different cams and a 2.0SC (68mm diameter) throttle body and his car produced over 200bhp.
This isn't going to happen for the majority of people modifying on a budget without the capabilities and experience that Neil has.
Most people are removing their 2.4 inlets in favour of their old 2.2 inlets and reporting back that the car pulls harder (more torque) with the OE inlet.
Torque is what counts on the road. There's no point in having 10 billion bhp at 6500rpm! Its unusable power and revving the tits off the engine like that isn't going to do it any favours. Torque is what drags/pushes you along the road and gives you that feeling that you are accelerating positively.
I was quite disappointed when I first drove my car after the developement work had been carried out. The car felt gutless and I was revving well upto the red line. My car dropped almost 20lbs of torque once the inlet was fitted and mapped.
My advice is leave it alone and concentrate on the exhaust system from front to back in the way of a 2.5 inch system and a Piper/dBilas 4-1 manifold.