I had a guinea pig called Bubbles when I was a kid. She squeaked like crazy, hated human contact, got straw in her eyes and covered the garden with pellets of ‘used food’ so I couldn’t play football without shoes on. I don’t remember getting her neutered like we did for our cats, so I guessed that guinea pigs were different to cats and dogs where castration can change behaviours. A quick google says my hunch was right, it won’t change their behaviour in any way!
So basically, I don’t know. But the internet says no.
Much of the body’s communication occurs via hormones. Castration disrupts an important part of this system, so for the generic mammal, I would expect some differences in behaviour, at least in relation to reproduction (e.g. in the vicinity of potential mates or competitors). No idea, though, to what extent hormone signaling in guinea pigs differs from that in other species.