What to upgrade first on a track or fast road car, why brakes matter before power, what Demon Tweeks covers, and the MOT, insurance and safety mistakes that cost more than the parts. Last checked: 17 August 2026.
Quick answer: upgrade in this order
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Upgrade in this order: brakes and tyres first, because they are the only parts that make you stop and turn faster; driver safety next if you are doing track days; suspension only once the car is stopping and turning properly; engine breathing upgrades last, with a remap if airflow changes significantly; cosmetics and noise upgrades last of all.
Where to buy performance and track parts in the UK
Demon Tweeks is a UK retailer covering brakes, suspension, exhausts, induction, intercoolers, turbo parts, seats, harnesses, helmets, race suits, oils, wheels, tyres and trackday accessories. The key is fitment and intended use. A pad or coilover that is brilliant on a track day can be terrible on a daily commute, and vice versa.
Before you buy, check the part is listed for your exact model, year and engine. Verify the warranty, the returns policy, and whether any part needs a remap or additional hardware to work safely. If you are unsure, ask the supplier or speak to a workshop that fits this kit regularly.
Brakes: the first upgrade that actually matters
On the road, the factory brakes are usually good enough for the tyre grip. On track, repeated hard stops overheat the pads and fluid, which is why a stock-braked car feels fine on lap one and terrifying by lap five. The right upgrade is high-temperature brake fluid, a track-biased pad compound and fresh discs. Braided hoses improve pedal feel and reduce the rubbery sensation under heavy braking.
Big callipers and larger discs only help if the standard brakes are thermally overwhelmed. They add weight, need bigger wheels and are expensive. Most road-and-track cars are better served by the right pad and fluid first. Check the pad's temperature range, because a track pad that needs 200°C to work is dangerous on the road in winter.
Suspension: why cheap coilovers ruin cars
A coilover is a spring and damper in one unit. It lets you adjust ride height and, on better units, bump and rebound damping. The mistake is buying a cheap set and winding it down to the floor. The suspension then has no travel left, crashes over bumps, pulls the wheel alignment out and wears tyres in 5,000 miles.
A good coilover has a matched damper, corrosion protection on the threads and adjustment you can use on the car. Buy for the damper quality, not the maximum spring rate. For a road car that does occasional track days, a quality fast-road spring and damper kit is often a better compromise than a full race coilover.
Exhausts, induction and the remap question
An exhaust only frees up power if the engine is restricted by the original system. On many turbo cars, the downpipe and catalyst are the bottleneck. A sports catalyst or de-cat downpipe can unlock power, but it also changes emissions and may fail an MOT. A simple cat-back exhaust adds noise with little power gain.
Induction kits are the most oversold upgrade. A sealed cold-air intake can help. An open cone filter sucking hot air from the engine bay loses power. Intercoolers matter more on turbo cars: a larger, more efficient core keeps intake temperatures down and power consistent. If you change the downpipe, intercooler or turbo actuator, the engine needs a remap to run safely and make the extra power.
Track safety: seats, harnesses and helmets
A standard road seat is not designed for the lateral loads of a track day. A bucket seat holds you in place, stops you bracing against the wheel, and makes the car easier to drive consistently. But it needs a proper frame or side-mount, and the mounting must be strong. A harness is only safe if it is anchored at the correct height and angle.
Helmets are non-negotiable for most UK track days. Check the organiser's required standard — usually Snell SA or M for track days, FIA 8859/8860 for motorsport events. A helmet has a finite life; the foam liner degrades. Buy new, not second-hand, because you cannot see crash damage inside a helmet.
MOT, insurance and the law
The MOT noise limit is 74 dB for many cars, but track-day limits and local noise cameras can be stricter. Removing or bypassing the catalytic converter is an MOT failure on petrol and diesel cars. Changing overall rolling radius by more than about 2.5 percent can affect speedometer, ABS and traction control. The car must not sit so low that the bodywork or tyres foul the suspension. All of these are modifications and must be declared to your insurer.
Common mistakes we fix in the workshop
Open cone filters in the engine bay breathe hot air and lose power. Track pads on the road are dangerous because they need heat to work. Coilovers set too low leave no suspension travel and cause constant alignment issues. Wheels that do not fit the car cause vibration and bearing wear. Exhausts with no resonator drone on motorways and can fail noise tests. Harnesses mounted incorrectly can compress the spine in a rollover.
Frequently asked questions
Are performance parts legal on UK roads?
Most are, but the car must still meet noise, emissions and construction-and-use regulations. A decat or non-resonated exhaust can fail an MOT. Stiffer suspension and wider tyres must not foul the bodywork or suspension. Declare modifications to your insurer, or a claim can be refused.
Do I need a remap after fitting an exhaust or induction kit?
Not always for a simple cat-back exhaust or panel filter. But if you change the downpipe, intercooler, turbo actuator or intake manifold, the engine is running outside the factory map's expected airflow. A remap then protects the engine and unlocks the gain.
What is the best brake upgrade for track days?
Start with high-temperature brake fluid and track-focused pads on fresh discs. Braided lines improve pedal feel. Bigger callipers and discs help if the existing brakes are thermal-overloading — but track pads are noisy and poor when cold, so they are not ideal for daily use.
Will coilovers ruin the ride quality?
Cheap coilovers often do. A properly damped adjustable coilover with sensible spring rates can ride better than worn factory shocks. The problem is owners setting the car too low and too stiff, which crashes over bumps and pulls wheel alignment out constantly.
Are braided brake lines MOT legal?
Yes, if they are correctly made, fitted and the right length for the suspension travel. They must not chafe or tighten at full droop. Most quality UK kits are TÜV or FMVSS compliant. A cheap unbranded kit is a leak risk and an MOT failure waiting to happen.
What helmet do I need for a UK track day?
Most UK circuits accept Snell SA or M rated helmets up to a certain age. Motorsport UK events usually need FIA 8859 or 8860. Check the organiser's exact requirement before buying. A well-fitting helmet matters more than a fancy badge.
Can I fit a bucket seat on the standard rails?
Rarely. Most bucket seats need a vehicle-specific frame or side-mount. The seat must be solidly mounted to the floor, not the original sliders if they are not strong enough. A harness bar or cage is needed if you fit a harness, because the forces on a shoulder harness mounted to a normal seat belt point are dangerous.
Do wider wheels and tyres affect the speedometer?
Yes, if the overall rolling radius changes. A taller or shorter tyre alters the speedometer reading and can affect ABS and traction control thresholds. Stay within about 2.5 percent of the original rolling radius unless you know the car can be recalibrated.
What oil should I use for track use?
Use a full synthetic oil with the correct viscosity for your engine and a high-temperature HTHS rating. Some engines need specific ACEA or OEM approvals. On track, oil temperature rises more than on the road, so a good cooler and correct level are just as important as the brand.
Where is the best place to buy Demon Tweeks parts in the UK?
Demon Tweeks is a UK-based motorsport and performance car parts retailer covering brakes, suspension, exhausts, induction, seats, helmets, oils, wheels and track gear. Check fitment, warranty, returns and delivery before ordering, and make sure any part you choose matches your intended use — road, fast road or track.