I understand your point but we don't have sufficient infos at this moment..&how lo is lo?

For the same engine diameter, if the by pass ratio reduced from say 0.7 to 0.25 and pressure ratio increase from 22:1 to 30:1,there could be quite a difference in thrust and exhaust gas speed.

A good example: I read that the french mirage F.1 in clean(no external load)condition can slightly exceed Mach1 at sea level without afterburner. The engine  Atar 9k-50 is a turbojet(zero by pass) with pressure ratio of only 6:1

Mirrage 2000, said to be able to compete with F16 has M53 engine with by pass ratio of 0.2 and pressure ratio of about 10:1