I have not seen anyone on this site use a Holset, but i know they are popular turbos for imports. Some company in china has been producing knock-off Holset turbos with Holset's logo, and tag on the compressor. Holset has recently raised a law suit on this company.
http://www.myholsetturbo.com/video.html
http://www.myholsetturbo.com/video.html