The manifold is a bunch of money and would spool the turbo a bit faster if made right but as mentioned, lots of heat and they tend to crack much sooner than a cast manifold, it is more for the racer mindset or showoff, to me at least.
There is a very reasonable cast manifold in the works and it all goes well it would be the wise choice for a street driven machine if you want lower maintenance.
The DP is not hard to build, I will make my own from what I have or start from scratch, even with a cat, flanges, etc....$200 in materials max.
The rest of the piping is really not needed, much simpler versions are easy to make for a good price.
On the very low end we might have a bolt on solution for just over $2k but I would budget more like $2500, pure speculation but by somebody that has been around a very long time, made my own kits, have wholesale accounts, know what it costs to ship, time to make things, test them.....A really nice EFR kit for $2500 would be a great price, if closer to $2k a hell of a deal.
That does not include final tune but today we can do that via data logging and email, dyno really not needed unless you just want the bragging rights, really good tunes generally are done in real world situations.