jakermc

I'm not sure what you are calling a 'stage', but the benfit of a Vram engine is torque at lower rpms. Whatever 'stage' you are referencing has little impact on performance. The valve size is what drives hp at the upper end of the rpm band and the Vram drives performance at the lower end.

Here is the best description I have seen on the Vram. The author, Steve Timmins, built the engine in my race car:

http://instant-g.com/Products/36Conversion/VRAM.html

Kolbjorn S

simply that at 5,000 rpm the air flow increases by a vacuum-operated section opening up a set of shorter pipes ("stage 1" or B below). At 5,800 a "tuning flap" opens a further set of short pipes thus joining the two banks of inlets ("stage 2" or C below). At revs < 5,000 rpm the air flow goes through the longer intake pipes (A below). Here's an illustration of what it looks like on 993 models after 8/95. Before this it was only "1 stage", I believe at 5,200 rpm, dating back to the 964 RS for which Porsche originally patented this technology: