It actually is a great manifold in my opinion. Driggsy and I got into quite a discussion about whether the AMG manifold was really suitable for a turbocharged car. I could see his point but at the same time I was told by my friends in the know that standard Cyclone's were used on NA Dynamic 4 Galants in Europe with good results so I figured why not treat the AMG Cyclone to some boost and see what comes out in the wash.
I've been extremely impressed with it on a mildly tuned 16G car. It is old technology that has been surpassed by stuff like variable cam timing and and it is true that for the cost, there are cheaper ways to make power. But even so, to someone like myself who has slowly been brought around to the concept of a more orthodox, fun and reliable 300-350 hp build as opposed to the 600 awhp jackstand Queen build, this particular part makes a huge amount of sense.
The car is noticeably quicker with the AMG Cyclone installed. Strangely, despite the huge plenum I felt that the biggest advantage was midrange torque/power but that could arguably be due to the fact that I'm still too chicken sh*t to install my 264/272 cams for fear of mucking up the perfect idle I've been enjoying for the past 18 months. I'm pretty sure that cams would allow me to take much more advantage of that plenum and significantly improve the top end.
If these things were not so rare and expensive they would without doubt be a staple of the factory upgrade engine rebuild blueprint.