“Where, then, is boasting?” N.T. Wright is forthright in this section of his commentary on the value of letting Paul be Paul (to use an expression from Jimmy Dunn). In particular, here are the things Wright thinks Paul denies: that boasting has anything to do with the normal human boast about self-righteousness; that the “Law” is a general moral code humans use to establish themselves before God; that “boasting” is the legalist’s claim with God of their worthiness. Instead, Wright puts the text in its context:

Where then is the boasting returns to 2:17-24 where Paul went after those Jews who thought their possession of the Torah gave them a leg up with God and over the Gentiles. Most importantly, Paul is teaching his readers how to read: his Jewish readers (probably “hearers”) have read the Torah as a piece of election; Paul reads the Torah as a piece of faith; and the implication is potent — anyone who really reads the Torah, Paul is saying, the way it is supposed to be read comes to terms with a relationship with God by faith and not by “doing the works of the Torah.”
The point is made clear in the middle of our passage when Paul says God is not the God just of the Jews; he’s the God of all. Why? Because all, regardless of who they are and where they live and on and on and on, can trust God in Christ. All. But that relationship is established by faith, by trust, and not be the “works of the Torah.”
And it is bolstered by an innovative use of the Shema (“Hear O Israel. God is one. etc”). Since God is One, the way of coming to God is the same for all: that way is the way of faith. God as “One” can be used to emphasize “election” or “God’s availability to all” and Paul chooses the second option. Quite suggestive for each of us to think about.
So, again, there is a great advantage in having the Torah: it gives the reader and hearer a chance to hear the summons of God to enter into the family of God by faith. Read in this way, Paul says those who trust God, whether Jew or Gentile, “uphold the Law.”
Issue: in v. 27 when Paul says the “law of faith” he is not using nomos (“law”) in the sense of general moral “principle,” of the Torah of Israel that shows the centrality of faith. In other words, the Torah, yes, but the Torah as lived by faith.