I dont know exactly how it works, all i know is that its 1/3 of the price of a KO4 conversion and it makes power. I still think that a single turbo setup would kick ***. I wish i had a S4 then id figure out how to do it.

 

i guess u simply tie up the tubes that go from the turbos to engine, and from engine to turbos. in sequential setup they are connected on the same line. there should be some kind of switch that channels the air through either of two. or it runs constalty through both, but only one is actually spinning. then u program CPU the point at witch the tubos switch... like at 3,000 first starts to level off while the other one spulls up, and both curves should meet at same level at let say 3,500 RPM. after that first quickly shuts off.
i think u can get more out of a turbo if you program it for a short RPM range. if it only works for 2,500-3,000 rpm range, u can put higher boost, cause u do not care about smooth curbe throughout whole range. u can have it spike high for short period of time.

 

all you would need is a BOV atteched to the intake pipe of the smaller turbo that is open when the bigger turbo kicks in and the smaller turbo can no longer contribute. this is how the skyline is setup.