any of run the hedmans or similiar y pipe configs know the best way to run the two small pipes into a single 3.5" pipe? and seal it? any adapters to do this?

Well not sure if this is what you are looking for but here is what I did. I'm running dual cats. I have two 2 1/2" pipes that "y" into a Mufflex 3.5" cat back system. I used a Flowmaster Y250350 "y". Hope this helps.

thank you that will work perfect. I tried searching for that but nothing close even came up.

this is with hookers but you get an idea, muflex has all different size pipes, adaptors and what not for making your own stuff too...
shown, muflex y pipe & muflex 3.5" ystem with spintec muffler