I promised @orangeblossom to share my impressions and thoughts on the Mid Box delete.

First, this confirms something I've long suspected. As Jaguar added Catalytic Converters, they didn't alter the rest of the exhaust system to account for the cats. The Mid Box and the Resonator/Silencer part numbers are the same regardless of year. Since the honeycomb structure of a catalytic converter acts as a muffler, a no cat car will be louder than one with a single set of cats, and the US spec four catalytic converter set up will be even quieter. So keep that in mind as you contemplate this modification on your car.

Overall, I give the delete a thumbs up. The replacement pipes from Simply Performance were easy to install because they come in two sections secured with band clamps which makes it easier to get everything lined up properly. They are a little lighter duty pipe compared to my new Bell Intermediate pipes, but still nicely made.

The two key benefits -- One, there is a noticeable difference in performance and I imagine in fuel mileage. Two, there is small alteration of the overall sound. Small enough that anyone outside of myself would likely not notice. The exhaust has a nice little English sports car burble which is very pleasant at idle and initial acceleration, but is otherwise not even heard above 25 mph (from the driver's seat with top down).

I wish I had done this 20 years ago when I first contemplated doing it. If you have 4 cats, there is only upside as far as I can tell. If you have 2 or none, then my previous comments on whether you have a coupe or convertible, and what you want to achieve will come into play.

I won't be putting the Mid Boxes back in, because in addition to liking the results so far, the mufflers sound like they are full of sand when you shake them so they'd have to be completely replaced if I did.

In order to get the exhaust sounding a bit more interesting will require removing the rear resonator/silencers and replacing with something to tune it. I believe I will be following @Tibbetts lead because he also has the four cats, and is very pleased with his set up.

 

Mine came with the midbox delete already done. It wasn't loud enough for me. Then one of the exhaust pipes broke at a weld and I finished the job of leaving open exhaust after the cats. That's a bit louder than what I want. If I ever get to the point of doing more exhaust work on mine, I think I'll leave it straight piped after the cats but run an X pipe that dumps in front of the rear wheels.

 

Regarding an X-pipe you might find this useful info:

https://www.jaguarforums.com/forum/x...3/#post2739485