They'd only take a few seconds to catch up once they felt Cell's energy clash with Vegeta's.Cell was already pretty far away from Piccolo. Everything around Gingertown was miles of wasteland but Cell was already deep in the florests.
At least, Trunks wasn't amazed by the fact that Vegeta could go SSJ. We don't know how much accurate can Cell data be since he doesn't even know that Piccolo could regenerate. Actually, Cell's focus, attention and concern relies on Vegeta, Piccolo doesn't come to his mind in his thoughts. At best, he considered to fight Vegeta something risky, but doesn't mean he can't win by blowing up the planet or stuff like that (but would be off character considering that the ones he want to absorb are on the planet).With Piccolo in hot pursuit. And he had ample data on the pre-RoSaT Trunks that couldn't beat the androids. Future Vegeta couldn't even go SSJ, other than in anime filler.
He states he killed him before and him kill him again right now in front of Piccolo. He slaps Trunks, no dif.We don't know whether it was base or SSJ Trunks the one that Cell killed, we don't even know if he had the chance to defend himself, as it happened off screen.
It could be twice he kill Base Trunks as Trunks was in his base form when he made that statement. Also, in your case is even more subjective, because you go with Trunks being more powerful 3 years after, how do we know which Trunks was the one that Cell killed? Either way, you can't be completely wrong about this and I give you that.He states he killed him before and him kill him again right now in front of Piccolo. He slaps Trunks, no dif.
Why would you assume Base Trunks? Cell isn't thinking, "Oh, I'll kill you now! Oops you transformed. Shucks, guess I have no chance."It could be twice he kill Base Trunks as Trunks was in his base form when he made that statement. Also, in your case is even more subjective, because you go with Trunks being more powerful 3 years after, how do we know which Trunks was the one that Cell killed? Either way, you can't be completely wrong about this and I give you that.