I am about to upgrade my dob gt450 manifold (standard dob manifold) to the new r-spec DOB manifold (for the big Whipple). I will let the used one go cheap.
http://www.departmentofboost.com/vbull/forumdisplay.php?5-GT450-3v-Manifold-Tech-and-Install-Info
As of now, till the last couple manifolds out of this batch are sold they are $1995 for a new one. The next batch will be going up in price (gt450).
I can get you a new one if you like or offer my used one for $1300. I will throw in the tensioner pieces that are another $75 for that price and it will sell fast.
With the used manifold you should be able to get one going for around $3k. This one uses the oem 07-12 gt500 blower and will make all the power you need with that stock motor. If you have a built motor I have a tvs that will get you to 700 no problem and will bolt right on the gt450 manifold
For a few extra bucks I can swing down to Houston and do the install and tune. Did a couple down there