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I leave them all in place. As much as I'd rather look at a nice engine, the LS 's engine is not....well....."nice". The covers almost never need removing, and when they do, they're easily removed. I bought a 100 pack of the clips for a couple of bucks on Ebay, so no worries of running out. I've seen posts where people have done some custom paint work of the covers. The HKS supercharger kit comes with some nice covers :
Personally, I'd rather see a beautiful set of REAL intake runners than all this plastic crap. However, everything under these covers is pretty ugly. I will probably leave them on since they come off so easily and may contribute to a cleaner and quieter engine.
I removed the passenger side plastic cover in order to use Group 24F battery (which has reverse terminals as compared to Group 24 batteries). Group 24F batteries are more common than Group 24 batteries and often at a lower price, everything else equal. Additionally, removing the passenger side plastic cover makes it easier to disconnect battery for routine work on the car without the fear of setting off airbags or triggering false alerts.
I believe there are other threads on this topic. In one of them, I recall reading that the covers on the sides are needed to channel rain water away from some of the parts underneath... Have not verified or tested that but I was not motivated to remove these on the 460 (but have been tempted on the 430).
I thought it was only the cover for the battery (the small cover on the left most corner on the passenger side) that must be on to keep rain from dripping onto the battery and engine compartment. The rest three large covers are more for cosmetic reasons to be on. On a GX460, in comparison, Lexus just supplied the center cover, leaving the left and right sides open. Taking off the side covers on the LS460 makes it look similar to the under hood of a GX460 - easy to conduct routine maintenance work. Of course, taking the side covers off the LS460 is an individual choice and would not be recommended by Lexus. Sort of doing it at your own risk, if any.
I've given it some thought (removing the covers). It's just a pain to remove everything to work on the engine, the reason I haven't removed them is because thankfully I almost never have to work on the engine...so why bother? But I have considered removing them...I may do it when the car gets a little older and starts needing under the hood attention but right now at 166,000 miles, the thing has been flawless.
Under hood engine covers... needed?
