ESS goes further than that (ts2+ and I think they do ts3 on request).
But that all is nothing compared to this custom turbo build with 800+HP :dizzy: (yes.... on the wheels that is :!: )
http://www.bimmerboost.com/showthread.php?35632-M54B30-801whp-881wnm-World-record!!!
(in a e46 though, but that is (was) the same engine)
And still a 'reasonable' torque curve (i've seen much worse/extreme in supra's etc)
But that all is nothing compared to this custom turbo build with 800+HP :dizzy: (yes.... on the wheels that is :!: )
http://www.bimmerboost.com/showthread.php?35632-M54B30-801whp-881wnm-World-record!!!
(in a e46 though, but that is (was) the same engine)
I will hopefully soon have a machine shop set up like they used in that link. I have the ability to make all the bits in bobs Manifolds pipe work. Just need someone local to me with the engine building knolage who fancies doing something similar???