But you wont take one crosscountry unless you want your dental fillings replaced.

 

I put mine to the floor at least once a trip if I have room. Anything less and the Gods of speed frown upon you. Anything more and the law does. Just took it out to see if today's wheel bearing replacement was good and my little 420 hp will pull very hard up through 70+ from a U turn. Not mind numbing like I'd expect 510 to but pretty darned good. This winters project of getting an actual posi rear should make it so much more fun below 50 mph where it wants to spin.

It sounds really, really bad, trust me. I will take some of what I said about the stock box back. It does sound pretty good at WOT, subdued but good.

 

I have the Mina backend system on my XKR which came with the Performance Active Exhaust system. The car has more punch and a somewhat deeper louder tone. I will try to record it over the weekend.

 

Was thinking about that. But that's always raised a question for me: since a pulley swap is relatively simple (and I understand the basic physics of why it would help)... why doesn't Jaguar put the smaller pulley in there to begin with? I've heard it's not great for engine longevity.

And thanks, Q&C, for the shout-out about my affection for the XK. It's true.

Oh, and my top speed in the car so far is 142 MPH. I-15, central Utah. Some kid in a new Camaro SS trying to show me what's what, and we can't have that. (But I gotta say, that SS was fast as F***). And it was me, not my XKR, that begged off at that point. I'm sure it could have hit the 155 limiter no problem. And as I've posted elsewhere, if you live anywhere in the LA/OC area and you haven't done Angeles Crest on an early weekday evening, you really haven't lived. Get some Asian kid with a BMW i8 who knows that road better than you do and you learn pretty quick what your car can do. (Or what you're personally willing to do.)

So yes I want it a little faster. Guess I'd love XKR-S numbers without the look, which I'm not fond of.

 

I think I would rather see how much power the ECU is pulling out of the combo before changing stuff for performance. I've noticed that mine absolutely love cool temps. Get it below 70 and it's an animal. Over 85 and it turns into a much tamer dog. I think the ECU has a very tame built in safety curve and with a little heat it pulls a ton of power out.

A while back Mandrake was having a conversation about the merits of different I/C combos to keep the intake air cooler. I think I would pursue that before exhaust for performance. Exhaust tone is the soul of the car. Few folks see how well it performs but they certainly hear it.

 

Interesting about temps. I was also thinking as I was driving up above 7000 feet how altitude might also affect all this.

With you 100% about the exhaust note. My great fear on an exhaust tweak would be that I wouldn't like what I ended up with, and I imagine that wouldn't be easy to undo.

I, uhm.... am not quite sure what you mean by an "I/C combo."

 

Where are you in the LA area? I can listen in person.

 

Intercooler.

It runs the compressed(heated) air through a heat exchange to bring it back to static temperature.

 

pk144,
I also have a 2010 XKR with the Mina exhaust, and I added the x-pipe. I find the Mina exhaust considerably quieter than the oem back box (which I might go back to), however, the addition of the x-pipe gave the sound a deeper, richer, tone. I did the pulley/tune a while back, and read many posts that said that the x-pipe addition was the way to derive the extra horsepower supposedly generated by the pulley/tune. I'm not sure it feels any stronger, but my ego does! And by the way, Ralph's car does sound different than mine, louder and a bit raspier, not quite sure why. I got together with Ralph this afternoon. You ought to join us sometime.

 

No crucifying is intended. However an exhaust mod is just that... a mod to the exhaust. That won't give him what he is asking for. So there are two choices left: extremely expensive modifications or just buy the Vette.

 

I realize that we are a small community helping each other, so here is my contribution.
We should really question our expectations to come to a satisfying answer.
As a luxury sports/ refined sports, 300hp would be a bonus. 400 a barn-stormer, there are many great cars that have lived with that, think of the many Ferraris, or even Aston.
Then there is the lightweight body and the insane lowend torque that ferrari et al could only dream of. Its twice as fast as an A8 and even corvette in the 50-70mph. I.e. its twice as fast in overtaking. The exhaust doesnt sound like a BMW, it sounds like a reserved cat. It wont embarrass you when you drive in a funeral procession, or sneaking in late at night. If you want more than this, where will you draw the line of happiness. Many would be happy with the looks alone.

Its stealth luxury and sports.

 

Granted yes exhaust mods lead to more noise (free flowing cats / non oem mufflers) etc ..however what is wrong with modifying a XKR jaguar with XKR-S parts I don't see an issue with that and PK would be guaranteed an extra 40hp

 

Here's a 5.0L XKR fitted with an XKR-S exhaust (rear muffler and mid section with x-pipe), 200 cell cats and a custom tune (guess who from) it's making around about 600HP and goes like stink, not to mention it bangs & pops like an F-Type.


While it might not be everyone's cup of tea, this is an example of doing it right...

 

I thought that the X pipe alone gave a marginal but noticeable increase in power. but it could have been imaginitis.

i'd start there. It was essentially stock for the XKR-S, so they did it for something.

 

After like 110, my XK started to feel a light in the front end, does anyone else notice that when getting their car up there in speed?

 

110 I do regularly, it doesnt require more than 80hp. No my car is firmly planted and at 110 it may as well be doing 70 in a toyota/lexus. It cruises at 110. Thats on michelin tires.

 

Rock solid up to 150. Actually didn't feel much different vs. 100 mph. Hands off steering wheel solid.

 

Driving through Kansas/Oklahoma/New Mexico I noticed how incredibly easy it was to drift up to 100. (Dangerous, given the cops.) Felt rock solid. At 140 I was driving dead straight, still felt good but I didn't go through a single turn so I couldn't comment on handling.

 

exactly the situation I ran into when modifying mine. Gutted the 2nd half of the cats, did bigger diameter pipe from the cats back and opened up the rear box a bit die the larger pipe. Deleted the valves as well....it's purrrrfect....a joy to hear when throttle is down, no drone and almost perfectly silent when cruising highway speeds....almost wish it was a bit louder as my tires are louder than the exhaust at cruising speed on certain roads

 

Hendo what do you mean opened up the rear box

Correct me if I'm wrong the cats are a dual set up containing a 400 cell & 600 cell ?
Which one did you eliminate/gut