Burnt Plastic smell when drive over 4000 RPM

[StealthSonic]

Hi guys, I recently noticed a wierd plastic burnt smell when I drive my car over 4000 rpm. It smells like hot engine oil or tranny oil and I can only smell it while driving over 4000 rpm for more than 30sec. Below that I won't smell it even if I drive my car for over an hour.

Smell comes into the cockpit and goes away in few minutes after I lower the rpm. Something is leaking?? Temperature guage is normal and radiator fluid is green and full.

I just had my oil and filter changed lastweek and I checked the oil level yesterday and it was between two dots on the dip stick. No smoke coming out of exhaust and I'm pretty sure I did a very clean oil change (not a single drip drip onto the manifold B pipe.)

Also no rough idle sound or trace of oil leaking in the engine bay.

It just seems strange to me.
Any one wanna give a shot?