If you're sensitive to heat, cut back on the gochujiang and gochugaru. I used them per the recipe and we enjoyed the result. (Tissues were on the table!).
I didn't like how the vacuum-packed noodles broke up while soaking. There wasn't one piece longer than an inch after draining. Next time I think I'll get dry udon and cook them maybe a half hour early, so they can cool and drain. A splash of water should separate them, before I toss them into the wok.