I don't mean to be critical or anything else. Just asking if you are running without any engine cover at all.
No, I don't use my engine cover at all.
I tow with my truck and I had substantial heat soak issues when I first towed with it in 2006. Removing the engine cover made a significant difference as it essentially acts as a blanket laying on top of the engine, holding heat intimately close elevating the temperature of the intake.
The last thing you want when looking for maximum towing power is a HOTTER intake air charge.
And, I think while not pretty it looks better without any sort of cover in that it looks functional and serious without any fluff.
Now, if there were a good looking cover for the '05-'06 I would have possibly considered it but reducing the detrimental effects of heat soak take priority for me on these trucks.
Anything you can possibly do to help the engine compartment stay cool not only helps the engine but again all of your rubber and plastic components.
That's another reason a cold air intake made of metal is a bad idea...heat soak. Plastic dissipates heat faster.
An engine is basically an air pump and the greater amount of COOL air you can get in (and get out with less restrictive true dual exhaust) the easier your engine makes power. And, keeping your intake as cool as possible (even if it is only a few degrees) makes a huge difference in the amount of de-tuning the computers in these trucks do when the temperatures rise.
You can see the effects of heat soak using an app like Torque with a bluetooth adapter which will tell you your incoming air temperature.
But anyhoo, no I haven't used my engine cover since I removed it years ago.