I know of hardly any tuning shops or products solely dedicated to the most most recent generation XKs

 

a pulley upgrade helps alot and didn't require an ECU upgrade so you can for the most part stay under the warranty radar. .Eurotoys has a good selection of goodies.
Look here:
http://eurotoysltd.com/catalog/produ...oducts_id=1325

They also sell some nice exhaust upgrades that will likely sound better but probably wont help your numbers all that much.

 

Contact avos on here for a bigger better twinscrew blower and 200hp

 

Did the upper and lower pulleys, exhaust and lowering springs from Eurotoys last Spring and noticeable different from SOTP. Definately pulled harder. My XKR is there at Eurotoys now for Custom Air Intake and ECU Tune. You can also port the supercharger but I won't go that far. I highly recommend Mike at Eurotoys.

 

@Quaker13
What sort of increase are you looking for?

 

You can talk to nameless performance too , they're one of vendors .

 

50-100hp

 

If it is the upper end that is of interested (so about 100 hp extra) then there is only 1 way, and that is to swap your roots type supercharger for a twin-screw. I can help you with the stage 1 kit I have, and that starts (in it lowest setting) at about 100 hp extra
You can change pulleys and reach 180 hp extra even (no extra charge, just the cost for a pulley which is about $80 and a belt for about $25).
Here is a link with some more details on the twin-screw and the kits on how these numbers are achieved:
https://www.jaguarforums.com/forum/showthread.php?t=42059

To even reach 50 bhp extra with the stock Eaton blower might be more difficult than you might expect (without NOS of course), and it would be nice if some could prove it with dynos (like ghostriderxkr08?). Besides pulleys, much more is needed as the thermal load is increased exponentially (instead of linear) when spinning the Eaton faster. So after 1 or 2 pulls the system is so heat up that you are starting to lose power quickly, as the intercooler system is just not build for this increase. So you might get there, but you have to change a lot, not just pulleys.

In a nut shell, either way (Eaton or Kenne Bell twin-screw), this range of power increase is not going to be cheap.

 

Based on the link provided earlier in this thread it looks as though i can achieve this for less than $2000 American not including installation. Does this sound correct? A 400bhp XKR can go as high 500 to 580 just with the change of pulleys and wheels? This seems crazy.

 

That the webpage shows a number for increase does not guarantee that you get it! I have bought here in the past also a pulley system, and I didn't gain at all (read almost nothing), and this experience is shared with others as well.

You only get a little but more power lowered, but not top end. Anyhow I would ask some dyno proofs form others on the forum, there should be some after a decade of pulleys available one could think.

Anyway, you need to do much more than what just the link suggests (or let someone proof what you can get), so you will need to spend more than $2000 (with uncertain results). If this is also the price range you are looking for, then there are no other options for you (besides NOS) unfortunately.

The minimum required would be pulleys, probably bigger exhaust and sports catalysts (check with nameless) work on the intake, and maybe porting the Eaton or at least good intercooler cooling with an alky kit for example.

This all goes into the $4000-$5000 to (maybe) get 50 hp extra with the Eaton, I don't know as I ditched the Eaton after the pulleys and porting didn't give me anything to write home about...

Good luck!

 

Reason I go to buy Xkr was increasing horsepower becuase I saw this. So I should not rely on them?

Paramount performance in uk with a 2007 xkr with exhaust with new racing cats and upper supercharger pulley and remap *at 508 horse power.
*
http://www.youtube.com/watch?v=BWNzx5LfmEg
*
Top gear with an older xkr with pulley and exhaust .* Commentator says it feels quicker in the video.
*
http://www.paramount-performance.com...t_384k-001.wmv

 

The figures are first of all from PP themselves, and second these are hard to interpret. You miss the pre dyno(s), and they show a calculated bhp figure. Do you know what %drivetrain loss they used? Or how the bhp is calculated?


I can guarantee you by changing pulleys that your butfeel will notice a power difference (and this is already good enough for many, so let me be clear here), but as mentioned this is only in the lower end, and what you get in power will diminish after several runs as the intercooler system can't handle the heat load. It looked more like a commercial then a true evaluation of the power difference imho, especially as the power difference was actually pretty low back then for that PP car.


You make the choices in what you want and where you feel good with, if you feel comfortable with what PP offers, than go with them I would say, but if you want more assurance of the extra horses and what that means then you need to do some homework imo, and I give merely some attention points…

(PS, the individual parts from PP added together in the XKR dyno would cost $5767 without VAT and fitting, and as far as I am concerned no idea what this brings in extra hp, could be 50 or 80, who knows?).

 

Very comprehensive Avos. Thanks