From this photo it seems the S55 has a TF015 (?) turbo (Mitsubishi).
This is the flow chart of a TF035:
But we don't know compressor sizes etc, so probably not bringing us any closer...
I can't find any information of a TF015 turbo, the only TF turbo I can find is the TF035. But to me it doesn't say TF035 on the turbo in the pic, does it?
The numbers I can read from the designation is:
TF015HI 4W-11HE17-6.0
Or could it possibly be:
TF035HI 4W-11HE17-6.0
The latter makes more sense as the TF035 is a Mitsu turbo:
http://www.mtee.eu/products/turbocha...harger-line-up
The number should decode as follows:
TF035: Turbo Family
4W: No idea
HI: Shaft and Wheel combination
11HE17: Turbine and compressor sizes (a "normal" TF035 usually has a 10-14 size compressor - and a "normal" TF035 supports around 240hp)
6: Turbine housing A/R