The R-44 Raven 2 is rated at 205hp MCP & 245hp TO/5 min. It is derated from approx to 293 HP per the instructor that I had at the Robinson Factory Course.
In the factory course, they showed us the main rotor head from an R-44 where the owner routinely exceeded the MP & did external loads well over the R-44's max gross of 2500 pounds. How that rotor head stayed together is a mystery.
The course gave me a better understanding of why the limitations are in place. Yeah, the R-44 has power well beyond the MP limitations. When you exceed it you run the risk of a catastrophic failure of components especially in the transmission and main rotor system at some future date.
I agree with those who say "don't let a red line kill you" however, you don't over torque or over temp a turbine. You don't fly past the VNE. Most of understand those red lines are there for a really good reason.