So having bought my first XKR (which still hasn't arrived) I dont know what to expect performance wise except what ive read or been told. So given a couple simple upgrades will bump the car over 400hp here is my question.

To those who have done this, is there a noticable difference outside of different exhaust sounds ?

Im a musclecar guy though have owned Jaguars since 1977. In my mind a performance car should have at least 400hp and while I would love to boost this thing to 600 with the twin screw kit I just cant pull the trigger yet considering I am just getting the car.

So any thoughts or comments would be appreciated.

 

I have added hp to 3 of my cars in the past and regretted it on each occasion. Yes, you get more power, but there always seems to be a trade-off in terms of smoothness and general 'feel'. I have sworn never to go down that road again, tempting though it is

 

I installed aftermarket cats and a new exhaust. The performance bump was noticeable. I haven't dyno'd it yet, but it has to be somewhere between 5-10%. If it were smaller than 5%, it probably wouldn't be noticeable.

Yes, my XKR now sounds amazing too.

 

Can't have too much horsepower so I'm pickin' up what yer layin' down :-)

But.....

If you researched the car then you already know that it'll be faster than the vast majority of muscle cars from yesteryear and as fast or faster than at least some of the current performance car offerings.

I'd drive it a bit and see whatcha ya think before doing any mods....although a performance exhaust system is hardly a major engineering change that'll cobble up the car.

I dunno. I'm always looking for more power as well but as I grow older I'd be more inclined to *buy* a car that already has the level performance I want rather than *modify* a car to the the level of performance I want.

(Famous last words heh heh heh. )



Cheers
DD

 

As a rule no, but you might notice a little w/twin screws(kidding).

I added almost 60hp and 58tq to my vette and did not really notice, though when I changed gear ratio(2.59 to 3.07) it made a real difference.
60 hp sounds like a lot, but my 0-60 was about .3-.4 seconds faster and few people I know can tell that kind of difference.
But I watched a shop do something that still makes me laugh today, this guy had a 928 at this shop and he kept saying the car was sluggish, shop could not find anything wrong. After the 3rd time, shop guy said he found the problem and had fixed it and added the dyno showed a 50hp difference. Guy drove the car around the block and came back saying he really could feel the difference, paid and left. I asked the guy at the shop what was wrong with the car and he said nothing was wrong, but he was tired of the guy complaining about nothing.
Moral of the story is, sometimes the only difference is in our minds.

 

Most of the easy upgrades i.e. bolt on pulleys etc, will give you more power but in the mid range, where you need it most IMO.

Best way, change the exhaust and cats, bottom pulley and then a remap, you will notice a difference.

 

Truer words were never said. It also seems that the more expensive the mod, the more power it 'must' deliver. An easy bolt on makes it more attractive too.

 

It's called the placebo affect.

 

Yes, sometimes sold under the Obecalp tradename.

 

Going to a smaller pulley on my XKR is the only "performance upgrade" I've done on any of my past cars that has actually yielded clearly noticeable results. With intake, exhaust, PCM tune, and other "freeing up HP" mods I've done on my previous vehicles I think it was always more of a mind game, and the mods never really quantified when I tried to test at the track.

 

Changing just the exhaust will not gain any noticable change, changing the cats will give you more but again you will not really notice the difference, you really need to do a combination of mods to notice a real difference.

Most people change an exhaust just for the noise, and who can blame them for that

 

Yes - simple upper pulley upgrade. Cost me about £250 here in the UK, and added a real punch to mid-range kickdown acceleration. No difference to the exhaust sound, and the car remains really tractable in low-speed town driving. And - good news - no noticable difference in fuel consumption when driven the same way as before. Go for this one.

 

So I guess I will ask who else sells the upper pulley ? I did a quick search and found a guy in GA but even though he talked about making then selling them and being a sponsor on the board there is nothing on his website showing the product for sale or the pricing. They look like the make alot of supercharger parts and has a couple testimonials about Jags but again stuff for everything BUT Jaguars. Who else, preferably in the US, sells the pulleys ?

 

Supercharger Upgrades - Jaguar XKR Performance Parts

 

You may be interested in this writeup I did a while back:
https://www.jaguarforums.com/forum/x...entures-46329/