The 2009 XK is an upgrade in power for me, but the excessive road noise made me not want to drive it. Sure, I can turn the stereo up, but then you cannot have a conversation. New tires seems to be the first place people go to reduce noise. There is some reduction in noise at a high price. My past experience with RX-8 models is that sound deadening insulation is a far better bang for your buck. Road noise is caused, in my opinion, not by high decibels, but by certain frequencies. You need to dampen those frequencies. You need to dampen vibrations.
I used this product: Second Skin Spectrum. Worked great! There is a substantial reduction in road noise. You have to buy their spray gun to apply this product. All you need is one gallon. I bought three to make sure that once I started this project there would be no stopping. Their website was not very helpful with determining quantity. I still need to pull up the carpets and coat those areas.
You can see the areas I coated under the car. I used three coats. Any metal that was exposed was cleaned and coated. I also coated any of the insides of fenders I could get to. Masking tape is necessary.
Most of my road noise was coming from the front tires. This is no longer the case.
I have received much help from this forum in the past and I hope I can add to the knowledge base.









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Weird, road noise was never a consideration for me and I have a convertible. I don't even notice it.

 

I find the road/tire noise high as well (doesn't stop me from driving the car though) - it can be applied using a brush too, probably the way to go on the car interior.