My XRK 2007 when I press hard the accelerator over 180 km / h produces a burning smell that disappears just release it when the speed drops below 170 kmh . Someone knows the cause of all this ? Thanks in advance

 

Is it more like a rotten egg smell? And are you smelling it from the exhaust?

 

No like a rotten egg but like a dress burned by an iron.

 

All the Hondas and Toyotas you just smoked???

 

Your description is of a fabric burning smell. I would raise the car on a rack and carefully examine the underside of the body near the exhaust. Look for char markings. Carefully examine the exterior of your catalytic converters for heat discoloration. Your cats might be clogged. A heat shield might be misplaced.
There is no "fabric" on the undercarriage of the car to char. "Fabric" is confined to interior space. After a high speed 180+ run you could take a non-contact thermometer and look for hot spots in the interior, paying particular attention to the area at the front of carpeting. If you find a hot spot, then peel back carpeting to confirm location. Ultimately, you will address the problem from beneath the car as all hot spots, above coolant temps, are caused by exhaust.

 

I read that break pads could smell like carpet burning... Did you brake hard after accelerating hard? Maybe brake pads?

 

It could just be old organic matter heating on the exhaust. Mud, plant matter, etc. I agree an infrared sensor would be a good idea. Your cats might be getting very, very hot if they are still the originals.