i have a question has anyone seen a s5 built twin turbo using the stock ht18s and something else. i have a hybrid that has a larger compressor and is using the ht18s turbine and housing for the hotside i was wondering if i could make it a bi turbo???

 

these are the turbos. the housing on the engine are ported large street port with and exhaust overlap exhaust has been ported out as well, its a s5 block and the rotary assembly has been balanced and the housings are pinned for strenght

 

From my very limited turbo knowledge... I don't think two FC turbos would be a good idea, it'd be hard to spool them both, and even harder to plumb it all. If you want twins it seems that going for FD twins is easier. Though a lot of people don't like twins at all because of the complication for controlling them efficiently.