Increasing gluten content -

If I wanted, say, 14% gluten content in a flour to make a particular recipe but only had flour with 12%, would I achieve the same result if I just added vital wheat gluten to the mix (in the right quantity) instead of actually using flour with 14% gluten content?  It seems like it should be the same, but I don't know if there's any sort of chemical reaction or changing of the bonding of the gluten to the rest of the flour particles that makes it impossible to put it back together again.

I'm trying to get a good bagel, have been unsuccessful so far with the recipes I've tried, but have one from "Inside the Jewish Bakery" that calls for flour with 14%-14.5% gluten. I'm not getting the chewy texture of a good New York bagel nor am I getting a particularly nice crust despite boiling, using malted barley syrup, etc.

Thanks!

Philip