TT-RS: 450 Nm/1600-5300 rpm
RS5: 430 Nm/4000-6000 rpm

That is what RXBG meant i think....with the TT-RS you have more torque over a much wider range than with the TT-RS ... that's the reason for the good time of the TT-RS...

TT-RS: 340 hp
RS5: 450 hp

That makes the RS5 so fast at higher speeds...it just logical that the RS5 with more ccm and more hp is faster at higher speeds...