The exhaust sounds killer now! On the test drive with your brother, we startled a few people that had their window down. The sound now matches the look of the car.

 

Hi Mike,

Great that you chimed in.

The explanation was not meant for why the shop didn’t print the dyno slips with the normal correcting, but more to give a breakdown of the gains, as I would have expected actually a higher result (especially if this was an even sharper tune than normal) with sport cats.

When looking at the figures, Viezu’s tune+pulley and Milteks sport cats on russduka’s car made about 40 rwhp more, yet Matt in Housten for instance made almost 60 rwhp more with only the a tune+pulley. Here is his link:
https://www.jaguarforums.com/forum/x...e2/#post845720
(Off course Matt needs to confirm if his figures where corrected as well).


So question to you, what would you contribute to the tune+pulley and what for the cats? And why do you think the gains are lower than from Matt’s car?

 

sorry know this was directed at mike, but Im going to chime in and say i think when I go back to the dyno in about a month I know this car will put down more power. We gained hp and lb ft on every consecutive pull on dyno and this was basically all hot runs. I see the car putting down 560 to 570hp and 520 lb ft on that same dyno in about a month. Also just because milltek states that you pick up 20hp from sport cats no one has yet to confirm that. And when I purchased from mike he said milltek claims 20 hp for the hfc's but that cant be guaranteed since he doesn't know anyone who has verified it. They could actually be causing a loss in power for all we know. Either way im willing to sacrifice 10 to 20 hp of loss and still have an overall gain with pulley and tune and be able to keep the exhaust sound that this car makes now which is epic!!!!

 

I have seen the video of this and the one when they compare to the aston v12s vantage since I am subscribed to motor trend on you tube. I doubt it will outrun a gtr on the track and it really doesn't bother me. That's not why I purchased this car. If it was only about numbers I would have bought a gtr instead. But I cant see myself behind the wheel of a Nissan. I have to much emotional attachment to the jaguar brand and the cars they manufacture. Plus the driver experience I believe is more raw in the xkr-s gt. but maybe that's just me. To each his own.

 

Depending on the track you can keep up with a GTR. My car with coilovers, tune, and a proper race alignment has no problem with stock GTRs on a road course without a lot of super tight low speed corners. If its a tight track their 4WD will kill you.

But like you said I cant see myself driving a GTR.

 

I could, and looked seriously at it, but it's awful as a street car in London. Even in 'comfort' mode, your teeth rattle. And the tramlining of the run-flats is scary. A Dynamic Pack XKR is far nicer to drive.

 

There was some slight correction, as can be seen on the stock dyno pic in the bottom left hand corner. It was only a .986 atmospheric correction at that time. Conditions were ideal but I may have been slightly heat soaked as I got caught in traffic on the way to the dyno, and it took me about an hour to drive halfway across Houston as I was stuck on the highway. But I am fine with this as it is more of a real world situation instead of a best case scenario.

I cannot confirm the correction on the post runs because I didnt take a picture of the screen and its not listed on the printed dynos. I'm sure I can ask Jerry as I believe all these runs are saved in the system.

Either way, I was wondering the same thing you are saying. Maybe the gains from the sport cats add nothing but sound, which is odd I think but possible.

 

At times reducing back pressure with to large of headers or exhaust can actually cause you to loose TQ and HP. This may be the case here, but if the sound is worth then so be it

 

All I have to do to increase the sound is drop the top.

 

 

+1


Jaguar is so much more refined and is a much better street car to drive and enjoy. My only main loss in selling my 2014 BE GT-R is the AWD. Where I live the winter can be harsh. It was a pretty expensive snow car and I had a great opportunity to make a few dollars on the resale so I dumped it--ok, I made a bucket full. Who knows, I may get another one if the right deal presents itself. I can do without the "boy ricer" image the car has acquired.

 

I think the gains on these parts indivdually are as advertised, but when you group multiple parts together, those gains do not always add up to the same amount. That is true for any car.

Not everyone of these R-S cars are the same either. Some have proven to not have the R-S 550hp tune in them, only the 510 tune. My guys at Viezu have confirmed this on a few that they tested. If they do not have the correct tune in them from Jag, they will actually gain more than the car that was properly programmed to begin with. I think Russ's GT had the right tune in it for sure. We were all surprised to see his original A/F's in the 12:3 area, most are richer than that.

Bottom line is both of you guys are happy with your cars and the performance. Don't let someone put doubt in your mind that this guy got more than you. Different dynos, different cars, different conditions all play a part. Not many cars can beat a 650hp car on the street!

All the best,

Mike

 

I agree on the GTR. I have driven 2 of them and they really seemed to lack character. I hated the transmission when coming to a stop and then leaving (clunky). I know they can upshift real fast, but drive one in Auto mode and floor it at 60mph, takes FOREVER to downshift to the right gear. That is because they have to go 1 gear at a time. I would much rather drive the XKR-S in S mode!

M

 

Yeah, there's some Weird ****™ that goes on with Jag software loads. My 75 is supposed to be limited to 174 MPH - it isn't, the limiter is 186, same as an R-S. I checked with the previous owner, and he never modded the car to R-S spec or had anyone change the limit. So, some standards, aren't.

 

Yeah, you can catch them flat-footed in Auto, even with the transmission set to 'R' mode - and I don't want to have to paddle-shift all the time. The ability to skip up to 3 gears at a time is a great feature of the 6HP28 box in the XKs.

 

Wow that is crazy! Since my car put down 481 to the wheels "corrected" in stock form I know I had the real tune. It is almost exactly 550hp when you account for drivetrain loss....a little more actually by 10-15hp.

I'm very happy with 540rwhp tuned, as you know the car pulls like a freight train. I will probably pass on the sport cats this time. I've had them on the last three cars I've had, but don't feel the need on the Jag. Exhaust sounds really great with the top down, especially.

If I had the coupe, I would probably go for it. Yup, I would.

 

The Jaguar trans is a real performance automatic, not the auto-manual like in the GTR. Just picture the inside of a manual trans and solenoids causing the shift forks to move to select a gear. Their is no way for the computer to decide what you really want (based on throttle demand) and then move to that gear (that fast). They have to go 1 by 1 until they get it. If you ran the paddles all the time you would be golden, but who wants to do that all the time?

Your car is bitchin by the way, love the color!

M

 

We have a DSG box in our Fabia vRS (same engine/trans as the VW Polo GTi) - wonderful piece of engineering, and really slick changes, but it is strictly sequential.

Yes, the 75 is a great package - as close as you can get (stock) to an R-S without the big $$$ and the bodykit. And there are only 20 RHD cars.

 

Np, Mike probably must have some sort of problem with me as he doesn’t answer me directly. Anyway, I really appreciate that you share your results here, which is great for the community!

I don’t know what Viezu claims in gains for your car for the tune+pulley, maybe it was even about 40 rwhp. It’s just odd with the added sport cats, as I would have guessed these would only add, maybe not 20 of course but at least some.

Here is what Viezu even has to say about the miltek ones:
“Jaguar Hi-flow Sports Cats work exceptionally well on remapped car, Jaguar Tuning, one of Viezu specialist subjects “
http://www.viezu.com/archives/tag/jaguar-xkrs-tuning

On the 4.0/4.2 cars sport cats do add some more power about 10-15 rwhp or so besides the extra noise, for which I love them myself very much as well.

Have fun, you have a great car!

 

I apologize Andre, I did not realize you needed your specific quote/name above my reply. Here is the same reply I gave before;


"I think the gains on these parts indivdually are as advertised, but when you group multiple parts together, those gains do not always add up to the same amount. That is true for any car.

Not everyone of these R-S cars are the same either. Some have proven to not have the R-S 550hp tune in them, only the 510 tune. My guys at Viezu have confirmed this on a few that they tested. If they do not have the correct tune in them from Jag, they will actually gain more than the car that was properly programmed to begin with. I think Russ's GT had the right tune in it for sure. We were all surprised to see his original A/F's in the 12:3 area, most are richer than that."


M