The M2 company that I'm familiar with went out of business some years back. I knew them for some FD performance products...downpipes, air-boxes, intercoolers etc., but not for turbos.
FWIW, I think the most popular alternative for owners wanting to stay with the twin set-up (sequential or non-sequential) is BNR. They do require an Efini 'Y' pipe that's modified by BNR.
http://www.bnrturbos.com/3rdGen.htm