I went with M3 side skirts. Looked at Mtech vrs M3 and for me, the M3 front looks much better. The Mtech on an e90 just looks so......square.
For the rear I wanted an Mtech with the option to go with different diffusers. But it seemed much more expensive to go with Mtech rear than just M3 rear, so almost went with M3 rear as well. Holy crap, I could just imagine all the childern driving behind me muttering to themselves, "That's not an M3". Whatever man.
Ended up ordering an Mtech rear from rockauto
http://www.rockauto.com/catalog/more...770&cc=1431851
Also, BMWmercedas parts sells the OEM rear mtech bumper cover for $475 and @$30 shipping. Would have been tempting to get an actual BMW part, but I already ordered at rockauto. Will update with the quality of the rock auto rear mtech and the SelmaUSA M3 front.
http://www.rockauto.com/catalog/raframecatalog.php
Was $333+$100/shipping. Looks OEM. All the "rep" covers I saw on ebay came casted (assuming) with a generic looking diffuser that I don't think comes off without cutting and I didn't want that.