To the original poster, been there.....done that. Save your money, install a drop in K&N air filter into your air box and buy a good aftermarket exhaust.

 

Wow, very clean, I like it!

 

The video of the bonnet/hood mods. The only 'benefit' I can see is that it makes it look "prettier" in some peoples eyes, personally I prefer original.

Think about it. If you lift the hood whats underneath? A great big bit of padding. So you either have to cut holes in that to allow more air in or the pretty holes are blocked. If they are blocked whats the point? If they cut holes it makes the hood paint discolour, you get a sort of black background mottling.

K&N filters. Pretty but not practical. You dont get greater airflow or better filtering in fact you get worse filtering because of the slightly larger pores. The pores let grit through and that in turn can and does pit the valves. You also have to oil them to keep up their 'performance' over oiling can lead to more problems. But they do look pretty to your mates when you pop the hood. Performance gain? Na. You would get more performance gain by removing the spare from the trunk/boot.

These are just my opinions and of course its your car and you have to do what you like best. No doubt someone is already heading for the keyboard to dispute what I say but Google and Youtube reviews on the K&N's and other filter alterations before you do. Pretty does not equal performance increase.

I will agree though that one performance mod you can do is the straight through exhaust. Makes the car twice as loud too. Jaguar moto = Grace, pace and space. You can drop the grace bit and increase the pace or buy a Mustang........

 

+1 on filters.
l bought a pair of K & N filters for my xjrs and before fitting just happened to hold them up to the light. The pore size in them is scarey. I still have them, stuffed away in the back of a cupboard unused.

 

 

You may have something here, I always wondered why I got so much power

 

For performance upgrades I did the following:

Custom made header
X-pipe coated exhaust which rusted in less than 3 yrs
Now a no mufflers in straight through (under axle) zaust
iridium plugs
BMC carbon dynamics air filter
changed coil packs
ran on royal purple fully synth
had both stock and LPG ecu's flashed
For 7yrs I ran with no cat convertors and bypass pipes but UK regs changed in 2015 so had to buy some 200 cell ones

 

Can’t change diff on 03 and newer. Computer won’t let you. That’s the one mod I would do in a heartbeat. 3.06s suck.

 

3.06's only suck until you are high speed driving. for example with E Types Jaguar used to down gear the diff for the USA export market and owners would wish for another high gear in the trans or an overdrive unit. installing the European spec diff gears solved the problem.

off-the-line performance has always been an American thing and catering to this and the desire for noise kept the American manufacturers out of any serious consideration as well engineered drivers' cars for a very long time. it also led to a lot of déclassé designs, modifications and behavior. a car modifier actually shared a great wisdom even though it was counter to what was his hobby and eventually business. can you fully exploit or truly master the existing vehicle specifications before you upgrade? or are you fixing an actual weakness that is sub optimal for the vehicle? finally, he said where are you going to be that you can exploit performance gains to a sustained degree? often modified vehicles become a bear to drive at anything regular, plus as my motorcycle riding friends tell me constantly, vibration and noise have a fatigue effect. they also fatigue your time and wallet. on a twisty road one can downshift and push the engine a little more and the extra fuel burned will never cost as much as an upgrade in terms of time, money, endless troubleshooting and reliability problems. and you will be experiencing the car as the people with multi-millions of funds and engineering intended.

one bit of wisdom from Steve Jobs was the story he told of a friend who tries to make a Volkswagen into a Porsche. in the end, he would have been better off purchasing a Porsche.

 

Taking car advice from Steve Jobs would be like taking computer advice from Carroll Shelby.

 

+1, and Mr. Shelby would probably do a better job with the computer too.

 

Here is one of my valves after 120Kmiles of abuse with K&N filters

 

interesting, thanks for posting that image. funny thing that i noticed with my car while running what one could say is the most protective (restrictive) filter. after over a year and close to 15k miles both the filter and air box were very clean as in like new. dust, grit and debris are often found at the bottom of the filter box in many cars and other makes. my XK8 is driven in a variety of areas where dust and SAND are prevalent, thus more would be expected. by accident or design our cold air intakes seem to be well shielded and consequently do not overwhelm the filtration system.

curious if you ever have your oil analyzed as silica levels sometimes indicate air intake contamination.

this is a good thing and means that modifiers should endeavor to retain the stock intake location. sometimes the manufacturer knows better.

 

I'm not sure what I'm looking at. Is that normal for a 120k mile valve or is that bad?

 

Am no valve specialist, maybe Frankc knows more, I would think its pretty good, never had any compression issues. I only swapped the engine as I had an accident, and it was easier to repair with the engine out, and as I had a 4.2 engine ready to go in I decided for that one...

All is relative, that was my point, If you live in a very dusty area, you may (may) want to think twice, still not for a XK8 imo, but for the XKR it is already worth upgrading the intake system, especially if you start increasing airflow as well (pulley etc), then the stock filter//intake setup is way undersigned. The original airbox setup with the air snorkel in the fender, does indeed reduce some larger particles, it is for that a good design.