Strange that it smells like sulfur, according to this: http://www.popularmechanics.com/cars/how-to/a536/2423551/ and a few other sources, it could be too much fuel is being injected under the increased load. This does makes sense though because the pcm may be trying to keep temps lower by injecting more fuel. Strange how it only happens under hard accelerations(and not eased accelerations), tomorrow I'm going to see what the fuel trim is like when I'm giving it wide open throttle. If its super rich then the cat probably wont be working as it should, which could produce the smell. (http://www.aa1car.com/library/converter.htm)
For me it doesn't smell a lot like sulfur, more like burning plastic, although I've never smelt sulfur.
Also after a spirited drive, the entire engine bay smells like burning plastic(similar to the odour inside the car), somewhat sweet smelling as well (hopefully not coolant)
I wonder what’s actually causing the smell, it has to be some sort of pcv/exhaust/vacuum line that's connected into or near the cabin air system, because when the hvac is off, the smell doesn't enter the cabin. Then again when the hvac is on, there is a 'vacuum' that's going into the car which could be sucking the smell in from the engine bay, but where the heck is the smell escaping from the engine! Or could it just be a plastic component that smells when it heats up. This is frustrating because it could literally be a hundred different things.
If I do buy a service manual I'm going to see what is connected to the cabin air system, or whats near the intake for it.
Maybe we could ask LMS what exactly they are doing with the fuel injection in their tune? It could lead us somewhere.
Anyways, back to pretending like the smell is just something that we pass by on the road