S-70 Black Hawk

S-70 successful helicopter for fire fighting and rescue operations
Вut not all modifications were successful...
Part of a damaged helicopter is seen lying near the compound after U.S. Navy SEAL commandos killed al Qaeda leader Osama bin Laden in Abbottabad, May 2, 2011.
Piasecki X-49 modification  by the scheme of the gyroplane has a very heavy tail  as seen in the video  

Тhe most promising way to power modification is compensation of torque by exhaust gases, allows use all engine power to increase speed.  Large area of the catalyst on the inner surface of the exhaust pipe provides more complete combustion of the  exhaust gases. This increases the environmental friendliness of exhaust. The main noise sources are operating mechanisms and high temperature exhaust  gases. Large surface area of the exhaust pipe allows more efficient cooling of exhaust gases. Multiple reflections of sound waves from the walls of the exhaust pipe reduce noise.