In any case, I prefer to take literally the words of Future Trunks, before calling him a liar.
Look, if you take literally the words of Future Trunks, you have to explain how he went from "in no way being a match" to "even I could fight them fairly well..." between chapters 348 and 355.
Chapter: 348 (page 6)
Trunks: "I... I can become a Super Saiyan, as well... but I was in no way a match for the two of them... their strength is unimaginable..."
Chapter: 355 (DBZ 161), P8.5
Trunks: “They’re also somewhat different from the androids I know…They weren’t as outrageously strong as this…Even I could fight them fairly well…”
Look, I'm not calling Trunks a liar just because I don't like what he says (and I wouldn't consider "a liar" someone that exaggerates some facts a bit in order to save the world), I'm saying that what he says at chapter 348 and what he says at chapter 355 is contradictory, and that I stick with what he says at chapter 355 because he had reasons to lie at chapter 348 (and before).
Now, you're saying that Trunks lied at chapter 355, that his claim about him being able to fight the androids fairly well was a lie, can I ask you what would Trunks accomplish by lying about that?
And if Trunks never lied, when did he power up between chapters 348 and 355? How much did his strength increase and how did he accomplish that?
If the power of the Base state of a Saiyan increases, the same happens with its levels of SSJ. It is very difficult to understand that?
No one is saying that the SSJ doesn't improve, what I'm saying (and its absolutely obvious because it's directly stated in the manga) is that the way to power up the SSJ forms is not the regular training that was enough to power up the base state, but a training around the mastering of the Ki in the SSJ forms.
In the 3 years from Yadrat to the Androids saga Goku's power only increased a 10-15%, we know that because Piccolo tells us SSJ Vegeta may have surpassed him, and once Goku discovers how to properly train the SSJ, in 1 year achieves much, much better results than Vegeta or Future Trunks in 2 whole years, even when they already knew Goku's trick to master the SSJ.
Not to mention it's shown he spend 3 days in a hospital after being pummeled by the twins on Trunks's special chapter. Can't post the scan tho.
Yes, he ended in the hospital because he lost the fight. Where do you think Piccolo would've ended after fighting 17 if instead of a Namek he was a human and had no senzu beans?
That doesn't mean Piccolo couldn't fight 17 fairly well.