the v6 s4 has two intake inlets and two exhaust because of the v design. the supra is an inline 6 so only one intake side. that is why they can do a single turbo conversion. also on the supra both turbos are on one side. in the s4 the turbos are on both sides. so if you want a single turbo you will have to route piping around the engine bayto the single turbo. that piping will take up to much space. also the supra has a lot of engne room. so you would be better of running two gt series turbos and have a custom setup made for them. they will produce good numbers. but at that power your internals will go very quik. those supras with that hp numbers are almost raceing motors. all of the engine componets are maxed out. nothing is stock on those cars. so possibly a rs4 engine block and s4 headers and do some internal parts. very reliable and powerful. my two scents.

 

here, just drop in a 2jz motor, like with these cars:
http://www.stlsr.com/forums/showthread.php?t=112153

 

Anything new on the gt28's kit, coming out for the s4, by atp?