Going fwd advice.

So I'm looking at the next steps for the v40, the problem is not many people have played around with the diesel v40s. So I'm happy with handling modifications and apart from anti roll bars I can source everything I need.
However there is a do88 intercooler upgrade available, but I've not done much in the way of upgrading turbos ect. So is this a worthwhile mod, what would would change in the remap after this?

The next is to get a high flow dpf for the exhaust as it's so restrictive, the guy I use who is very good has quoted in around 1k to do the dpf is this about right?

All I'm after is around 250/260 out of it so any advice would be welcomed!