Yes puma is stock fitting, although they also sell it with a vband. I have tried to keep all stock fitting parts so I can swap parts around easily for testing etc. The DHM is only designed to fit the turbo in the kit it comes with, but I wouldn't be surprised to find a stock fitting one for sale from at some point. I am having spool issues un-related to the mani/header so my results are hard to take as the word but from what I seen as is I wouldn't be comfortable saying more than +10whp and 200rpm earlier spool (and this is on my non stock turbo, again different).
Keeping the stock turbo as in did I upgrade it, or am I going to sell it? I have a different turbo and I think I will be putting the stock one up for sale.