I'm pretty sure Rosberg broke Schumi's lap record, Rosberg was like 1.13.9 and record is/was 1.14.3
The reason why it gets faster is because of downforce. On the longer tracks with bigger straights the V10s (esp in 2004 with ABS and TC) had an advantage due to more power and less downforce (better for acc), but in Monaco power doesn't matter as much and extreme downforce setting is used, which makes up the difference for lack of power.
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also Red Bull is sponsored by Infiniti if you didn't know.