Chapter: 498 (DBZ 304), P7.4-5
Context: after Boo disappears
Trunks: “Even if he really is still alive, it doesn’t matter! That jerk was helpless against Gohan! [Gohan] was about as strong as our Super Gotenks!”
Goten: “He was even stronger.”
Trunks: “Really? …Yeah…Just a little bit.”
Gotenks was equal to Super Boo and Gohan was smashing him. It's a pretty big gap despite what Trunks says.