Eaton have a newer design blower out, the TVS 2300, it has more twist on the lobes making it more efficient as well as 4 lobe rotors.
These guys are getting over 350hp out of a Porsche 3.6 air cooled with a M90
http://www.tpcracing.com/porsche-964-and-993-supercharger-kit.html
But water/meth injection is a must to keep the outlet temps under control.
I'm using an M90 on a 1.5 litre motor and anything more than 8psi boost the outlet temps go through the roof.
