Depends on the application. The information portrayed in this thread does not portray all the data, which is not so unanimously for an "87mm" Turbine in every application.
There are a few things to bring to light in this discussion.
1) There is 2 common "87mm S400" turbines, and 1 less common option. So with out specific technical data of a turbine, it may not always be an apples to apples comparison.
2) As a general rule of thumb, Compressor Inducer Determines Spool-up & HP potential. Turbine wheels & TH A/R determine where in relation to RPM the HP/TQ lands. (An easy comparison, is the common FMW profile of the 67.7x95 wheel vs the common 63x95 wheel. Exducer Dimensions and radius are nearly identical. The 67 will spool "slower", and require more energy to drive than the 63 if both were fitted with the same turbine.)
At FPE we use the 83mm turbine on small inducer setups, like the cast 63x95 & cast 67x100 wheels. Why? Because when we tested on the street and dyno with several 87mm turbine options there was little to no gain over all, over the 83mm turbine in the power range the Compressor could support, and their respective reliable power ratings. Regardless of application. Yet with our larger, and arguably more aggressive Billet Compressors, there is a significant difference in power and response with the 87 over the 83.
Caleb