From my research, it seems to depend on how your body reacts to
PMMA & builds collagen. I got .5" out of each round (2), to get to my goal of 1". That seems to be about average per round.
Age, diet, health, supplements, all play a part in how much collagen you build. There are even posts on here showing average gains.
I took Collagen, Vitamins A, C, & E, plus amino acids for 3 months after round 1 and gained .5". After round 2, I took the same for 2 weeks and quit. I still gained .5". So, it's a toss up.
*While I would never presume to discourage anyone from going through with
PMMA (although I would argue that in my case, I NEEDED to do it) I would never have done it if I had been 5.25". I was 4.5" at my Viagra-induced best, and probably more like 4.3 or 4.4" most of the time. So, I understand wanting to be bigger, but think clearly about it. You're already above average. Just my $.02