My '05 XK had just the right sound at idle and at full throttle. A sophisticated, Jaguar sound.

My '08 with the same drive-train does not sound sophisticated. In fact, gasp... I feel under moderate acceleration as if it were a truck engine. I used to have a booming resonance when accelerating at very small throttle openings, not too loud but, enough to bother my sensitive ears. I took the car to the dealer and they installed some exhaust bracing per a TBS.

That work simply shifted the range of the sound. Now acceleration is OK, but I hear the same "droning" at 70MPH while cruising. It bugs me as I do lots of freeway driving and can give me a headache over 2-3 hours.

I can not believe that Jag would have altered the nice sounds of the '05 to this one. I even looked under the car to see if maybe the previous owner put in an aftermarket exhaust but, it looks stock with a one-piece-dual-outlet rear muffler. So, I'm planning to take it back to the dealer to see what is going on. Before I do that, I'd like to know if anyone with the '07+, 4.2 l engine finds the exhaust similarly loud?

If this is how the factory designed them, I'd be surprised and would probably install some straight-through-dual-tip silencers ("Monza" comes in mind), just to cut off those sound frequencies.

Thanks,

Albert

 

nope, I do not find it to loud, actually I installed the XKR muffler to get the sound level up a little.

 

The easy way for you to find out is to test drive another XK!

 

I love the way it sounds, in fact I never heard a Jag (of any ilk before) and had no conception of how one would sound. I will say this, I believe there is a lot of Mustang GT in the XK exhaust tone.

Tom

 

Hey Albert--you're probably in the minority about this. Just take a visit over at my usual forum group (previous gen XK) and you will find most of the guys looking for ways to get more noise out of their exhaust. This was also true of the Corvette Forum I was a member of when I had my 1995 Corvette and is probably also true for any forums that are geared towards "performance cars". I couldn't believe the amount of people eager to fork over big bucks for an exhaust upgrade. In most cases what you get is maybe a couple of horsepower increase but a big increase in noise.


Doug

 

That's just it. It sounds like a Mustang GT with an aftermarket exhaust that is biased just a bit too much towards performance at the expense of civility.

I used to have a highly modified Mustang GT that I raced for a few years and the part-throttle exhaust tone of my XK most reminds to that one. I purposely set the free flowing exhaust of the Mustang for max performance, sacrificing cabin silence. With the Jag, however, I prefer a quiet, luxury ride that does not give me a headache. If I want a headache I take out my twin turbo RX-7, 500 HP and all, and it will give me a headache if cruising the freeways for anything more than a few minutes. Same kind of resonance, but a fair bit louder, from a very free-flowing exhaust system.

I'm suspecting now that much of the performance advantage that I perceive in my '08 over the '05 is, indeed, coming from this louder, free flowing exhaust. I'm pretty sure remembering that the '05 used separate rear mufflers vs. the single combined one for the '08.

I will stop tomorrow on my way home at the dealer, hoping that they have a 4.2 l either in their service or showroom. I still have a hard time to believe that they would tune the XK exhaust to be even slightly intrusive. That is not what I would expect from a luxo-cruiser, like the XK.

I may even be a slight exhaust leak that could cause that type of "droning". We'll see. I won't be able to leave my car at the dealer tomorrow but, just want to get an idea if this is normal or not. If it is, I'll probably get two twin tip Monza silencers that should give me just that little extra silencing that I need.

Something like the link shows, depending on the exhaust pipe diameter size.

Amazon.com: Pace Setter 95-9904 MONZA Dual Outlet Exhaust Tip: Automotive

Thanks much for the replies,

Albert

 

Hi Doug

Thanks for responding and, you're probably correct me being in the minority. But, I have modified many performance and race cars, and at this point I want one that does not give me a headache over the several hours of freeway driving that I do these days.

To free up the exhausts, on most cars, truly will get you very noticeable power increases. That would be the very first mod I would do in search of power. As an example, when I started to build up my 500 HP RX-7, the first mod was to take off the pre and main cats and replace the rest of the exhaust with a single straight through 3" resonator muffler with tunable Supertrapps at the exit. It allowed so much more fuel/exhaust passage that on my third acceleration I blew the motor, due to leaning out the fuel mixture so much.

Cars, like what Tom mentioned above, the Mustang GT 5.0 responded wonderfully to free flowing exhaust and cold air intake. Gobs of power gains. Also, I am not one of those guys who believe in the claims of the aftermarket manufacturers, I actually tested each change by doing acceleration timing at high speeds where increases in horsepower truly manifest. With my very successfully raced previous Twin Turbo RX-7 those tests were going from 60 - 160 MPH, twice in each direction. Ha...ha...ha... those were fun times... That car topped out with the 180 MPH speedometer fully pegged but, the calibrated real speed was "only" 172 MPH :-). My present twin turbo has considerably more power...

So, while I do not mind the least the sound racket (music to my ears) that goes-on with a high performance, modified car while playing on my favorite twisty roads, I do want a quiet, civilized ride when I'm going long distances. The '05 fit that bill. I may have to tame the '08, unless the dealer finds something amiss.

Albert

 

I'm not convinced the semi-active exhaust on the normally aspirated cars works as well as intended. I had an 07 and I think the valves used to stick and rattle so I'd randomly get too-loud, not enough flow or an annoying metallic rattle from the back end. I actually tried to source an aftermarket exhaust from the UK but they never managed to manufacture it (which reminds me, that particular vendor owes me about $1000).

I now have an 08 XKR and the active exhaust is beautiful - quiet burble at idle, practically silent while cruising and a nice deep explosive V8 sound if you plant your foot. And if you want it to sound like a V8 all the time - pull fuse # 19 from the fusebox in the middle of the rear seats which stops the butterfly valves in the rear pipes from closing.

 

Now, this comes as a total surprise to me. I have had no idea that my normally aspirated '08 might have semi-active exhaust.

If so, where are the valves located and what activates them? I guess the fuse indicates some electric, potentially computer activation?

That may be my problem. The more I think about it the more certain I feel that I have a problem that Jaguar would not possibly have designed the cars with this kind of exhaust resonance. As a matter of fact, no manufacturer of lesser cars would do so, which is where the after market comes in for those of us who wish to trade off.

Guess, I am really new to this car (2 months) don't even know that there is a fuse box in the "middle of the rear seats"?

Would appreciate your answer regarding the design and location of the valve.

Thanks,

Albert

 

the normally aspirated cars are only "semi-active" and the valves open in response to exhaust pressure. There's no way to check if they're working since they're all sealed up inside the rear muffler :/ But, as I said, I suspect they can stick and the fact that there's no way to inspect or service the moving parts seems like a design flaw to me. I'd recommend driving another car and, if it feels and sounds different, the solution may be to source a new rear muffler.

The supercharged cars are fully active and the butterfly valves (in the outside pipes) open up under control from the ECM depending on revs and throttle position - so "fuse 19" only affects supercharged cars.

 

Got it. Good info.

Thanks,

Albert

 

My sense is that the semi-active system in the XK consists of a simple flap that is held closed by a spring. Exhaust drone typically occurs at lugging low rpm or sometimes at a particular rpm cruise. The flap partially closes the exhaust causing exhaust flow to slow down a bit allowing noise to attenuate. Your description sounds like the spring may have broken allowing the flap to "flap" open. Your first remedy is to seek warranty muffler replacement.
Out of warranty, then a new muffler may be your remedy.
An aftermarket possibility might be a Dynomax VT muffler, which also incorporates an internal spring-loaded flap. These mufflers cost about $100 each. I installed these mufflers on another car with a MagnaFlow exhaust system that droned. They cured the drone and the car is as quiet as stock at normal cruise levels.

 

Yes, exactly what my problem appears to be. Lugging low rpm acceleration (around 2000) before they installed the exhaust braces and now at 1900-2000 cruising RPMs.

It is Certified car, still has over 1 year of regular warranty plus the Certified warranty. So, replacement should not be a problem. Appreciate the Dynomax VT recommendation, I will file it for future reference.

Thanks,

Albert

 

Stopped by the dealer, went for a freeway test ride and, of course, the noise was barely audible. I even told the mechanic that I could live with that level of exhaust noise. The dealer was only a few miles from my place of work.

So, I proceeded to drive the 150 miles to home. What I'd found that the more I drove it, the more obvious the exhaust resonance became. After about half way, once again, it started to bother me.

Not sure what is going on but, if the spring-loaded exhaust valve theory is true, it could be that as the whole muffler and the inside valve spring get heat soaked, it could stretch enough where even the minimum throttle required at around 70 MPH could produce enough exhaust pressures to fully open it, thus increasing the noise with time and heat built-up. Just a theory for the lack of knowing what is causing it.

I could not very well request the dealer to change the muffler when it was not obviously a problem during the test ride. He felt bad enough for not being able to make me happy; I had to reassure him that it was fine, I'd just have to figure things out and would probably be back with the issue.

Albert

 

@axr6 - Did you test drive the car before you bought it?

 

...for only a mile, or so, on the jammed freeway of San Francisco and over city streets. The car was a Certified one with low mileage, full warranty so, what could go wrong...???

BTW-I've just sent you a PM, asking about your satisfaction with the sounds of the Mina Gallery exhaust system. Looks like I will not be able to install those Monza tips that I was hoping to. They will not fit the present muffler configuration.

Albert

 

To loud?!!??! Oh my gosh, I love the sound of the exhaust on our 2007 XK!! It's gorgeous.

 

I have recently acquired a 2006 XK and am amazed that Jaguar can sell such a noisy car.
I have taken it back to the dealer and he has shown me that they are all like this.
I know from previous posts on this forum that not everyone is happy with this level of noise, I am also confident that some others at least will also desire a quiet XK in keeping with the Jaguar reputation.
The dealer has said that he will see if Jaguar produce a quieter system for other markets that could be fitted to my car.
I had previously taken it to an exhaust specialist designer fabricator to have a quieter silencer made. However they examined it and pronounced that it was 'not a Jaguar' and did not believe that Jaguar would intend to make such a noisy car, they referred me back to the dealer to get a new silencer fitted.
On boroscope examination they pronounced that the silencer had parts missing!
They turned my business away apparently because they believed it to be defective and a basis for a warranty claim.
I realise that many owners like a loud exhaust, I hope that for those that like a quiet relaxing quality car; there is a Jaguar alternative, failing this I will have an effective silencer made.

 

For the uninformed ... what is the physical configuration of the exhaust system on these later cars?

 

I love the sound my 2008 XK XKR