Welcome aboard. I was wondering the same thing after I bought my XKR as I had gotten very used to minor to moderate tweaks on my 95 Corvette. It seems like there are really very few enhancements that can be easily/cheaply done on the Jaguars. There are some aftermarket intakes out there ranging from about $150 to $300 but the consensus from others is that these may not really do very much. There are also some aftermarket exhaust systems but bang for the buck (bftb) is really dismal ($2,000 to get maybe 20hp?). The other item I have seen is a replacement supercharger pulley so that you get more boost. These are also a bit pricey but my guess is that this would be the best bftb in terms of improvement that you could probably feel. I imagine there could be substantial gains by playing around with the engine computer but I am not aware of any readily available devices to enable you to do this yourself.

I am sure that others will chime in here but compared with more mainstream muscle/sports cars like Mustang, Corvette, Nissan 350Z, Infiniti G35/G37, etc. there does not seem to be as much out there for tinkering on the Jaguars.

Doug

 

Maybe it's a good sign that Jaguar did a good job giving the best bang for the buck right out of the door without having to shell out MORE bucks for more go.

 

Jaguars computers are sensitive too. Some aftermarket products are not liked by the computers in the car.

 

My impression is that to get any seatofthepants gains for any late model normally aspirated engine you really need to get into the innards (port and polish intake, cam change, etc.). On the other hand I have heard that getting noticeable gains from turbo cars is relatively easy (add boost and minor computer reprogramming). I suspect that the same can be said for supercharged cars like the XKR so the supercharger pulley thing is probably the best bang for the buck assuming this does not harm anything else.

Doug

 

I have to disagree with the statement regarding these cars being "pretty tweaked already". It is quite the opposite, you may want to ask your new friend what he is basing that statement on. I know from first hand experince you can see 20psi of boost with no problems. You can make many improovements to your car, starting with a true fresh air intake system with the air filter assy in the wheel arch, a free flow exhaust system including free flow calatysts, a ported supercharger with a small upper pulley & a larger lower pulley, larger supercharger radiator with the cooloing system isolated from the main system & a seperate resevoir with an additional pump in the system, water methanol injection, reprogram your ecu, & port & polish the cylinder heads. In addition you can install a 3.27 rear axle ( tcm needs to be reprogrammed) as well as install a speed shift system ( sold by Racing Green Cars) so you can control the transmission shifting via buttons on the back of the steering column. This is just a list off the top of my head as to upgrades you can do, & I promise you it is like night & day. I see 0-60 times of just under 4.0 seconds. If you really want to go carzy there are twin screw superchargers as well as exhaust headers being developed. Wwith all of my upgrades I havenever had any ck engine lights or driveability issues.

 

Your points are undoubtedly all correct but these are far from 'tweaks'. These types of mods are pretty costly and definitely not for the casual 'do it your selfer'.

Doug

 

JGAXKR has provided the laundry list of what's available. Some credible owners on the other forums are posting claims of 600 hp. Air flow is the key. If you have a supercharged engine, the platform is there to add big chunks of power. If the engine is naturally aspirated, even the most expensive upgrades are going to be disappointing.

With an XKR I think the first and best upgrade is a pulley swap to bump up the boost. This seems to be the most popular modification. Anything beyond that and I would suggest you find some competent sources of Jag specific information. Just adding boost w/o adjusting for the air fuel mix and cooling is a receipt for burning piston tops and putting unwanted holes in your cylinder walls. gordo