Table of Contents
In this article on must have Jaguar XK upgrades, we’ll cover the modifications that deliver real change to how the XK drives, sounds and looks. You’ll learn which upgrades to fit first, what power gains to expect from a custom ECU remap on a supercharged XKR, why a sports exhaust changes the V8 note and how the right suspension setup sharpens handling. By the end, you’ll know which upgrades to prioritise and in what order, so every pound spent on the car delivers a real return.
The must have Jaguar XK upgrades cover four areas: engine and ECU work, performance exhausts, suspension and handling plus styling. The XK V8 responds well to better airflow, a sharper map and a freer exhaust. The X150 chassis transforms once the rubber bushes and standard springs are swapped out. This article walks through every upgrade that delivers a real change to how the car drives, sounds and looks, on both the X100 generation (XK8 and XKR, 1998 to 2006) and the X150 generation (XK and XKR, 2006 to 2014).
Shop our Jaguar XK Performance Parts (1998 – 2006)
Shop our Jaguar XK Performance Parts (2006)
Where to Start with Your Jaguar XK Upgrades
Every build starts with two basic decisions: what you, the owner, wants from the car, and which generation you have. An early XK8 has different priorities to a 5.0 supercharged XKR-S. The naturally aspirated cars want to breathe, so airflow and exhaust come first. The supercharged cars have a large reserve of power waiting to be released with a remap and a pulley change.
If you are new to must have Jaguar XK upgrades, start with two: a sports exhaust and a custom ECU remap. Together they change the character of the car without touching anything that cannot be reversed. As Jaguar specialists since 1986, we have built almost every variant of the XK platform, and that order delivers the strongest result for the money spent.
Jaguar XK Engine Performance Upgrades
The biggest gains sit here, especially on the supercharged cars.
ECU Remap and Engine Tuning
A custom ECU remap is the single most effective Jaguar XK performance upgrade you can buy. On a 5.0 supercharged XKR, a Stage 1 remap adds around 50bhp along with sharper throttle response and a flatter torque curve. Our Jaguar XK 5.0 tuning is written live to your car, so the file is built around your fuel grade, any existing modifications and how you drive. Stage 2 brings hardware in, such as a supercharger pulley or sports cats. Stage 3 builds on that with cooling and breathing changes and is best signed off on a rolling road.
For the older 4.2 supercharged XKR, the Jaguar XKR 4.2 remap is available either at our UK workshop in Bidford-Upon-Avon (get directions) or through our home tuning system, which lets you upload a file via the OBD port from anywhere in the world. The V-Switch home tuning device lets you switch between economy and performance maps yourself.
Supercharger Pulley Upgrade
On the supercharged XKR, fitting a smaller upper pulley or a larger crank pulley spins the supercharger faster, pushing more boost into the engine. Paired with a Stage 2 remap, the gains are obvious from the first prod of the throttle. The 4.2 and 5.0 cars have different fittings. Never run an aggressive pulley setup without a remap written to suit it.
Air Filter and Cold Air Intake
A free-flowing air filter and a cold air feed give the engine cooler, denser air. That means more power and lower intake temperatures under load. On a naturally aspirated XK8, this is one of the first changes worth making because the standard airbox is restrictive. With an exhaust and a remap, the difference is immediate.
Charge Cooler Upgrade
The factory charge cooler on the XKR copes under normal use. On a tuned car running harder boost, intake temperatures climb on longer drives. An uprated charge cooler or cooler pump keeps temperatures in check so the engine holds its peak power.
Shop our Jaguar XK Performance Parts (1998 – 2006)
Shop our Jaguar XK Performance Parts (2006)
Jaguar XK Performance Exhaust Options
The XK V8 is muted by the factory exhaust. A sports system unlocks the sound the engine should make.
Cat-Back Sports Exhaust
Every exhaust we build is fabricated in-house from T304 or T308 stainless steel, with titanium available for owners who want to save weight. You can choose between a resonated system, which removes specific frequencies and cuts cruising drone, and a non-resonated system, which is louder and rawer. Resonated exhausts suit daily drivers. Non-resonated suit weekend cars. Our Jaguar XK 5.0 performance exhaust is a popular choice for the X150 and fits straight onto the factory hangers.
XK to XKR Quad Exhaust Conversion
This is one of the most popular must have Jaguar XK upgrades on our books. Many XK owners want the four-pipe look of the XKR without paying XKR money for the car. Our XK to XKR exhaust conversion gives you the quad-tip rear and the deeper note that comes with the four-pipe system.
Sports Catalytic Converters and De-Cat Pipes
200-cell sports catalytic converters are a popular upgrade for owners who want a sharper, more characterful sound. They pair well with a sports rear exhaust to complete the look and the note. De-cat pipes are also available, but in the UK these are for off-road or motorsport use only and should not be fitted to a car driven on the public road.
Valvetronic Exhaust Control
Valvetronic technology lets you switch between a quiet cruise mode and a full sports mode from a button or a remote. It suits owners who want noise on demand and refinement when leaving the house early.
Shop our Jaguar XK Performance Parts (1998 – 2006)
Shop our Jaguar XK Performance Parts (2006)
Suspension, Handling and Brakes
Get the chassis right and the XK becomes a serious driver’s car.
Lowering Springs
The X150 sits better and handles better with a 30mm drop. The wheel arch gap closes, the centre of gravity drops and turn-in sharpens. Our Jaguar XK lowering springs are built for the 2006-on cars, with a separate set available for the 5.0 chassis from 2009.
Polyurethane Bushes
Factory rubber bushes soften with age. A Powerflex handling kit replaces them with polyurethane, which sharpens turn-in, cuts body roll and lasts far longer than the originals. The change in steering feel is immediate. For any XK over ten years old, this is one of the best must have Jaguar XK upgrades you can fit.
Wheel Spacers and Wheels
A 20mm wheel spacer pushes the wheels out to the edge of the arch for a more aggressive stance and helps fill the arches once the car is lowered. Lighter, larger-diameter wheels reduce unsprung weight, which helps both performance and ride.
Performance Brake Discs
If you are adding power, the brakes have to keep up. Tarox front brake discs for the XKR are heat-treated and hand-finished, giving stronger bite, less fade and a firmer pedal under hard driving.
Shop our Jaguar XK Performance Parts (1998 – 2006)
Shop our Jaguar XK Performance Parts (2006)
Top Jaguar XK Upgrades for the X100 (1998 to 2006)
The X100 generation has its own list of must have Jaguar XK upgrades. The naturally aspirated 4.0 and 4.2 V8s sound transformed with sports cats and a sports rear box, releasing the deeper V8 note that the factory exhaust holds back. Many X100 owners also refresh the front suspension mounts and fit wider 18-inch wheels for a more modern stance and better grip. On a supercharged XKR, a smaller supercharger pulley combined with a custom remap is the strongest combination for genuine, noticeable power gains.
Shop our Jaguar XK Performance Parts (1998 – 2006)
Shop our Jaguar XK Performance Parts (2006)
Must Have Jaguar XK Upgrades FAQs
What is the best upgrade for a Jaguar XK?
For a supercharged XKR, the best single upgrade is a custom ECU remap. It adds around 50bhp on the 5.0 cars and improves throttle response across the rev range. For a naturally aspirated XK or XK8, a sports exhaust and a high-flow air filter come first because they free up the V8 to breathe.
Can a Jaguar XK 4.2 be remapped?
Yes. The 4.2 supercharged XKR responds well to a custom remap, whether you bring the car to our Bidford-on-Avon workshop or use our home tuning system to upload the file yourself. We have been writing maps for the 4.2 V8 for many years.
How much power can a remap add to a Jaguar XKR?
A Stage 1 remap on the 5.0 supercharged XKR adds around 50bhp. Beyond that, the gains depend on the starting bhp of your car. The 4.2 supercharged XKR leaves the factory with 416bhp, so any increase is calculated from that baseline. At the top of our range sits the 650 package, which pairs an upper and lower supercharger pulley, an uprated charge cooler and performance air filters with a full custom remap for the biggest gains we offer. You can compare every option, from a Stage 1 remap right through to the 650 package, on our Jaguar tuning and remap page.
Are aftermarket exhausts legal in the UK?
A road-legal sports exhaust that retains the catalytic converters and meets noise limits is legal for road use. De-cat pipes are designed for off-road or motorsport use only and should not be fitted to a car driven on public roads. Non-resonated systems are louder than resonated ones and may approach UK noise limits, so check the system you are buying is road-legal if your car is used on the road. The UK Government guidance on vehicle modifications and insurance covers what needs to be declared.
How long does a Jaguar XK exhaust take to make?
Lead times vary by vehicle. If we have the system in stock, dispatch is quick. If we order it in from a supplier, lead time depends on their availability. If the exhaust is built to order, we make it at our Bidford-on-Avon workshop. Fully custom exhausts with no prior pattern are made on site with the vehicle present, so you would need to bring the car to us for that work.
Will Jaguar XK upgrades affect my insurance?
Any modification needs to be declared to your insurer. Failure to declare can invalidate your cover. A remap, an exhaust, lowering springs and pulley upgrades all count as modifications and must be reported.
Do I need a rolling road for a Jaguar XK remap?
Not for a Stage 1 remap, which is software only and can be written through the OBD port. Stage 2 and Stage 3 builds with hardware changes are best signed off on our 3,000bhp 4×4 rolling road, where we measure power and torque output and make final adjustments.
Why Choose Paramount Performance for Your Jaguar XK Upgrades
Paramount Performance is a division of VIEZU Technologies Ltd and has been tuning Jaguars since 1986. Our background is Jaguar and Land Rover, and although we now cover every major make, the XK model remains a daily focus. Every exhaust is hand-fabricated in our Bidford-on-Avon workshop from T304 or T308 stainless steel and titanium. Every remap is written by our in-house file writers and validated on our 3,000bhp 4×4 rolling road where needed. Our remaps come with an insurance-backed guarantee and a 30-day money-back guarantee. We ship parts worldwide and we fit at our UK workshop.
About the Author
Paul is the Retail Marketing Manager at Paramount Performance, responsible for promoting the Paramount Performance brand, its services and its growing range of retail performance upgrades. His role focuses on creating marketing activity that helps customers understand what is available for their vehicles, while also supporting the retail sales team with clear, useful content and campaign activity.
With the Jaguar XK, Paul’s focus is on helping showcase the tuning, exhaust, styling and performance options available through Paramount Performance, presenting them in a way that is easy for XK owners to understand and explore.