http://www.youtube.com/watch?v=E396u..._order&list=UL

 

Not sure is the short answer quaker, but I'd at least check out Nameless Performance, one of our site vendors who has done some top work on exhaust systems for our cars.
Gotta be worth a look and they're Stateside too

 

Epic loudness!!

I have a high flow catalyst downpipe set for your 2007+ XKR, but have yet to develop an exhaust on these cars. Not for lack of trying. I chased a guy down all the way to his house to give him our business card the other day. I don't think he was pleased that my '86 Volkswagen Van w/ Subaru Power could keep up with his 2010 XKR. :-(

So we could certainly use a car to develop from, either an R model or the naturally aspirated variant.

To make a note, most of the performance gearheads on the forum here agree with us that the catalyst is the first point to rework for performance gains and a nice ENGINE sound to your exhaust rather than the burble that you get out of a catback with less bang for the buck. But hey, if it's aggressive exhaust you want, the beauty of these systems is that you can just keep swapping sections out until you get to the level you prefer. We suggest to start with cats, add the back half of the exhaust and then a center section with X pipe or resonated X pipe muffler for the full effect.

Drop me a PM if you're in our area, we'd love to get an exhaust developed for the 3rd Gen XKR's.

Jason

 

Here's what we put together for a customer's 2004 the other day:

 

Nameless do you have a youtube or soundclip of your cats sound?