For a stock SR20 they are fine, in fact up to about 300kw they are ok, after 300kw they fall apart fast, I have loads of them in the scrap metal pile, most common problem is they shear all the teeth of 3rd, bend layshafts, split casings, snap input shafts, snap output shafts ectr... whole box pretty much becomes rubbish over 300kw (and thats on street tires not slicks)

RB box on the SR20 motor is the way to go if you want good reliability.