off topic: mounting tb before turbo, benefits and drawbacks???

[Chris Conlon]

> Most turbos do not have the compressor side seal required to allow
> them to live in a repeated high vacuumm state.  It can be ordered
> with SOME models..

Could someone please make some specific suggestions as to what brand(s)
and kinds of turbos can be had with a good enough seal? The possible
lag-reduction benefits of running a turbo this way are too much for
me to ignore. I'm looking for something about the size of a large
Turbonetics T-3 or a small T-4, if that helps with picking specific
turbos or manufacturers.

   Thank you,
   Chris C.