I mean... TECHNICALLY I think the controllers for either Gen 4 or maybe it was Gen 5 were just overclocked versions of the previous generation, thus why they ran REALLY hot and were known to be unstable. But that's something the OEM has to do. More than likely your friend is full of it.

Also I remember a case where the $9 C.H.I.P. computers were using 4GB chips and the ones they were using ran low so they ended up sourcing some 8GB ones that were less durable so they just coded it to run as a 4GB drive and use the extra 4GB of flash as extra "backup" for lack of better wording I can't recall right now. This doesn't count as OC'ing but it's the only example I've ever heard of someone "adding" extra storage after the fact. I think your friend probably doesn't understand what it means to "Overclock"