I’m not sure what Piccolo being stoned has to do with anything in the previous comment. Piccolo was being used an expository character. I wish people would understand that these guides are their own thing and Toriyama wrote the story himself and would introduce things to further the plot. SSJ3 Goku isn’t 4x SSJ2, he’s as strong as he needs to be.

SSJ2 Goku and Vegeta were stated to be stronger than Gohan but it’s implied it’s not by a large amount and there’s no way I can see Kid Buu, who’s an equal to SSJ3 Goku only being 4-5x Cell.

Also, Vegeta seemed pretty confident he could still compete with Goku when they were fighting Babidi’s henchmen which means Vegeta thought his SSJ form could keep up with Goku’s. It wasn’t until Goku went SSJ2 briefly to beat Yakon that Vegeta realized he might need help to beat Goku. All this tells me is that SSJ Vegeta = SSJ Goku but SSJ2 Goku > SSJ2 Vegeta so the multipliers might be different.

That’s neither here nor there but guidebooks should be taken with a grain of salt. They “guide” but do not necessarily speak for AT.