S400 74/74/AR1 / Stock , Twin setup?

Hey guys,

Im pretty new to all this AND Im from Sweden,,,
so I hope you understand what Im saying and can take a couple of dumb qestions...

I have a -06 cummins that I use 1/3 for daily driving,1/3 Towing and 1/3 Playing with it/Racing.

Still have the stock turbo on.

Im pretty shure I want twins... and now there is S400 74/74 AR1 ,none wg, for sale that planing to buy,, but then I got some second thoughts...

Will the s400 above be a good turbo under the stocker?
How much psi would I expect?
and Egt´s?

Is there a bettar second turbo alternative?
Or am I almost as good using a single 62 or 64 ?

I will use a smarty and 90-100hp nozzles together with the new turbo(s)

Im aim at 600-700whp.

Im really grateful for all help I can get from you,, Because I aint getting it here in Sweden..

I would go for a 64/71 you can make 700hp and still tow. The s400 you metioned has to small of an exhaust wheel for twins.