The gap is not due to compression.
I only ran it with the plastic piece installed for only 10 minutes, and then took it off because it was rattling. I installed again after shaving the plastic ribs but it still rattled.

Without the plastic, There is about a half inch gap between the diverter and the bonnet's sheet metal, and about a one inch gap from the front of the diverter to the the painted plastic hood scoop.

Way, can you please help to confirm with DDM whether the plastic piece is supposed to be in there or not?

 

I bought one too, did not take off plastic though because it did not tell you too in the directions.....? I added some rubber washers to the top under the screws to give it a little 'flex'.
I have only driven the car once after install, did not notice any rattles or rubs in that little time....

Way, please weigh in on this piece: Remove or not remove?

 

I drove the car up around 250 miles over the weekend with the hood scoop pieces all in place....

I have no rattling or rubbing as far as can hear or see.
Still waiting....

 

Sorry I can't keep up with all the threads.

Yes you are suppose to leave the plastic part on the hood, that way it will seal up.

 

Way, thanks for confirming.

I drove mine 1000+ miles this weekend including some track time. With the foam pieces, I don't get rattling, but I am getting some wear through the rubber piece on the right side where it hits a corner bit of the plastic.

I'll submit a photo later.