anyone have experience running one of these as a single? What kind of turbo are they comparable too (ex. 62/12, 62/14, etc. ). I see they now use it as their top turbo in their twin kit. I'm thinking of going with one of these once I do a box and injectors, and that way I can upgrade to twins someday if I choose to do so. The 3y/150,000mile warranty is nice. Also, do they use a 4"downpipe?