Another place to check out if you are looking for twin components (flanges and such) is http://midatlanticdiesel.com/ Llyod is a great guy to deal with and a payed vendor on this site. He doesn't have the twins parts listed on his site yet but he does have some of the parts available with more to come.
Joe

 

Daily driver compounds? Where should I start?
My stock turbo is in good shape, gonna keep it
I dont mind a little fabrication and playing with wastegates.
I was thinking K-31 spools faster than an S-400... right?

 

The k-31 will spool faster but not move as much air. You might want to check into a 14cm housing for your hx35. I opted to use the 12 cm housing with a modified wastegate as I couldn't see putting that much money into the stocker. I haven't had any issues in almost a year with my setup so I am happy. Building them is the easy part its the tuning that can be a PITA. Hope this helps.
Joe

 

Thanks Joe, its encuraging to see someone has already done this and is enjoying the results.
Could I use the existing banks big head wastegate and 12cm housing on the HX-35?
Any idea as to where do I source a cheap K-31?

 

The Banks Big Head will have to go. You will need to set the wastegate on your 35 to about 25 psi to start and the Banks unit is set way to high. I got my k31 off ebay from Air Flo. You will either need to open up your internal gate on the 35 or run an external gate to keep drive pressure in check.
Joe

 

with my tial 38mm gate my drive pressure is 1-1 all the way to 60lbs boost. thats with 25 from the primary and 35 from the secondary. i would like to hear drive pressures from someone that has opend up the stock wastegate passage to see the diffrence between an external and internal wastegate

 

olddodgetruck, where are you checking your boost pressures? Thanks, Sa.

 

i have my total boost coming from my head, boost from the primary in the cold pipe and drive pressure right before the secondary turbo in the manifold.

 

I would rather put the garrett 3782 over a BTH-3B or S400. Mine works nice and its simple to build and cheap. A ball bearing primary would be awesome too, you could almost get away running just a BB4294R as a single and I bet it would almost spool decently. The new technology is the garrett is abit head of the bushing/journal bearing style turbo. Of course time will be the test, as I'm beating on mine just to see if the ball bearings survive. The next best big thing to come to us diesel heads would be a large frame ball bearing VGT with adjustable turbine housing. No more need for twins.