I have actually found that if you give Penny both the sheath and the throbb it will be bigger then if you only use one option.Don't be such a cuteslut.
Still, since now Virection is a thing, there should be an option to give it to Penny. And Emmy... Still, don't like where she goes. Yep, Dell tailcunt scene is pretty nice.
SS overrides effects of Throbb. As Penny says, "it is almost as bad as I've expected Throbb to be".