This is quite kooky. I just picked up my 2018 "R" a few weeks ago and am perusing this site to educate myself about certain features and characteristics of my car. I have noticed that engine noise gets considerably louder (more than I expected) in the cabin during certain RPM's of "spirited" driving ..... and I'm noticing that the tech sheet above has a date of 4/14/2009 in the bottom right hand corner, which leaves me wondering if this is applicable to my 2018 year car and is an enhancement to what I'm hearing in those exciting moments of driving?

 

That diagram is from the AJ133 Technical Training pdf which came out in early 2009, shortly after the AJ133 was introduced.
Yep, your 2018 F-Type almost certainly has the Symposer.
It was fitted on all AJ133 (V8) and AJ126 (V6) from the get-go, and I understand it was discontinued on the F-Type (and I suspect all Jags) for the 2020 or 2021 model year.
See this helpful post for how to quickly and easily disable it: https://www.jaguarforums.com/forum/f...6/#post1553181
That is for a V6 but the V8 is exactly the same, just a little harder to access because it is further back and closer to the firewall.