Is it BS ? or can you really get a longer and thicker cock ?
Not that I’m small ( bit over 6 )  , but as probably most men , I wish I had an extra inch or two  
Of love making machine in my trousers.  

Put a pillow under her ass.  

Is that the muscles atrophy and if you take off the rings, she face-plants in her soup.  

to lengthen your penis. Everything that's out there is a scam. The length of your penis--erect or flaccid--is determined by the stretched length of the tunica albuginea, and this hits its maximum length at around 20 years of age.

Why would you want to.  I've actually had issues due to more size.  I say be happy with what you have, and not give one cent to scammers who prey on guys by making them feel insecure about our size and then selling the snake oil to fix the problem... and if you call within the next 10 minutes you get two more inches by just paying shipping and handling lol

can vary with the height of the girl, at least that's been my experience after bottoming out on some very short spinners.  I do best with 5-4 to 5-8.  When you get over 5-10, there's sometimes an echo coming from her pussy because you're not using it all.  Just my experience.  I'm sure John Holmes would see it differently. (That tells you how long ago I stopped watching porn - lol).

Even normal length can be an issue with some gals.  They don't like it smashing against their cervix.  However, many gals prefer more penis girth (diameter.)  

I've found no correlation between the height of the woman and the size of her vagina. I've been with women 5' 10" who were extremely snug and women 5' 0" who were more spacious...just sayin'.

Embrace your 6"

it was an exact science, just a general observation after seeing over 400 working girls.  There are always exceptions.  I have had some, too.  

Love your analogy...

I agree and I'd say thicker gives the woman a more full feeling. I'm pretty tight already and by no means need someone thicker to be satisfied though :p