A Stage 1 remap is the most popular form of ECU remapping, and the simplest way to get more out of a modern car without changing any hardware. It's a software change to the engine's control unit (ECU), it's usually completed in 60–90 minutes, and on the right car the difference is obvious the moment you pull away.
This guide covers what a Stage 1 remap actually does, what gains are realistic for petrol and diesel engines, whether it's safe, and what you need to sort out afterwards, including your insurance.
What is a Stage 1 remap?
Every modern engine is controlled by an ECU running software set by the manufacturer. That software decides how much fuel is injected, how much boost the turbo makes, ignition timing, throttle response and a long list of limits.
Manufacturers set these figures conservatively. The same engine is often sold in several power outputs, and the calibration has to suit every market, fuel quality and driver. ECU remapping adjusts that software to make better use of the engine you already have.
"Stage 1" means software only, on a standard car. No new turbo, no exhaust, no intake. If you're thinking of going further with hardware, our post on Stage 2 tuning and the parts it needs explains the next step.
How Mac Tuning approaches Stage 1
We've developed our own software for most vehicles, tried, tested and refined over a number of years of research and real-world tuning. Every tune we do at our Hertfordshire workshop is custom, and it's further tweaked for the specific car in front of us rather than being a generic off-the-shelf file.
What gains can you expect?
Gains depend on the engine, so there's no single answer. As a general guide:
- Turbo diesels tend to see the biggest improvement, particularly in torque. More pull from low revs makes overtaking, motorway driving and towing noticeably easier.
- Turbo petrols also respond well, with stronger mid-range and sharper throttle response.
- Non-turbo (naturally aspirated) petrols gain much less. A remap can still smooth delivery, but don't expect a big change on paper.
Industry figures usually quote somewhere in the region of 10–30% more power and torque on turbocharged engines at Stage 1, but the real number for your car is what matters. You can check it in seconds on our power gains check: enter your registration and it shows the expected figures for your engine.
Does a remap improve fuel economy?
It can, especially on diesels. Because the engine makes more torque lower down, it doesn't need to work as hard at cruising speeds. Whether you actually see better MPG depends on how you drive: use the extra power all the time and consumption will go up.
If economy is your main goal, we also offer economy tuning, which is set up specifically to reduce fuel use rather than maximise power.
Popular Stage 1 remaps: BMW, VW Golf and Audi
These are some of the most popular cars for a Stage 1 remap, in Hertfordshire and across the UK. The figures below are typical Stage 1 ranges quoted across the UK tuning industry, not promises: standard outputs vary by model, year and variant, and the condition of the car and the fuel it runs on play a part too. For the expected figures on your exact car, use our power gains check.
BMW 20d (B47 2.0 diesel): 320d, 520d and X3 20d
The B47 2.0 diesel is used in the 120d, 320d, 420d, 520d and X3 xDrive20d from around 2015 onwards, and most versions make about 190 bhp and 400 Nm as standard. A BMW 320d remap or 520d remap typically takes it to around 225–240 bhp and 460–500 Nm, depending on the exact variant. The extra torque is what you notice most, particularly when overtaking or towing.
BMW 20i (B48 2.0 petrol): 320i and 120i
The B48 2.0 turbo petrol in the 120i, 320i, 420i and 520i usually makes around 184 bhp and 270–300 Nm as standard, which leaves plenty of headroom. A BMW 320i remap or 120i remap typically lands at around 250–270 bhp and 400–420 Nm, depending on the exact variant.
VW Golf GTD and Golf 2.0 TDI
A Mk7 Golf GTD makes around 184 bhp and 380 Nm as standard, and a Golf GTD remap typically takes it to around 215–230 bhp and 450–470 Nm, depending on the exact variant. The common 150 bhp Golf 2.0 TDI responds well too, typically reaching around 185–195 bhp and 410–430 Nm after a Stage 1 remap. On DSG cars, gearbox tuning is worth considering alongside the engine.
VW Golf GTI and Golf R Stage 1
A Golf GTI with around 242 bhp as standard (the Mk7.5 Performance and the Mk8) typically goes to around 285–300 bhp and 400–440 Nm at Stage 1. A Golf R Stage 1 remap typically takes a Mk7 or Mk7.5 R (around 296–306 bhp standard) to around 360–380 bhp, and a Mk8 R (around 316 bhp) to around 390–410 bhp, with torque in the region of 470–500 Nm, depending on the exact variant. Figures at the top of these ranges usually assume 99 RON fuel.
Audi 2.0 TDI remap: A3, A4, A5 and Q5
Audi's 2.0 TDI comes in several outputs across the A3, A4, A5 and Q5. The common 150 bhp version (around 320 Nm standard) typically goes to around 185–195 bhp and 410–430 Nm after an Audi 2.0 TDI remap, while the 190 bhp version typically reaches around 215–225 bhp and 430–450 Nm, depending on the exact variant.
Audi 2.0 TFSI: S3 and A3 40 TFSI
The 2.0 TFSI in the A3 40 TFSI, including S line models, makes around 190 bhp and 320 Nm as standard and typically goes to around 240–260 bhp and 400–430 Nm at Stage 1. An Audi S3 Stage 1 remap typically takes an 8V S3 (around 300 bhp) or 8Y S3 (around 306 bhp) to around 360–370 bhp and 480–500 Nm, depending on the exact variant.
Is remapping safe?
On a healthy, well-maintained engine, ECU remapping with a properly developed Stage 1 map is safe. Problems after a remap usually come down to three things: an underlying engine fault that was already there, poor maintenance, or a sensitive engine that simply needs the power dialling back slightly.
That's why we carry out a dealer-level health check before every tune. If we find anything, such as stored fault codes, a struggling DPF or a sensor issue, we tell you before going any further. A remap won't fix an existing problem; it tends to make it show up sooner. If your car has diesel emissions warnings, our guide to DPF and EGR delete is worth a read first. A few things also help keep a tuned car healthy:
- Keep up with servicing, ideally with OEM parts (we can do this for you)
- Let the engine warm up before using full power
- Use good quality fuel, and the octane your car is meant to run on
For more on common worries, see ECU tuning myths debunked.
What to expect on the day
A typical Stage 1 visit looks like this:
- Health check. Diagnostics and checks on the car before anything is changed.
- Read and back up. We read the original software from the ECU and save it.
- Write the new file. The Stage 1 calibration for your engine is written to the ECU.
- Check and test. We check for faults and make sure everything runs as it should.
Most cars are completed in 60–90 minutes, though some newer ECUs take a little longer to read. We've covered preparation in more detail in Tuning booked? Here's what you need to know.
Software warranty
If your tune is ever wiped, for example during a dealer software update, we'll reinstall it.
Useful add-ons
If your car is an automatic, gearbox (TCU) tuning can sharpen shift times and help the gearbox handle the extra torque. Max speed limiter removal is also available as a £25 add-on to an ECU tune.
Remaps, insurance and MOTs
Do I need to tell my insurer?
Yes. A remap is a modification, even though you can't see it. UK insurers expect you to declare it, and not doing so could invalidate your policy or lead to a claim being refused. Premiums may change, and some insurers won't cover remapped cars, so it's worth checking before you book.
Will my car still pass its MOT?
There's no MOT check for ECU software. What the test looks at is emissions, smoke and warning lights. A properly developed Stage 1 map on a healthy car with all its emissions equipment working should pass as normal.
What about my manufacturer warranty?
If your car is still under manufacturer warranty, check the terms first. Some manufacturers may decline engine-related claims on a modified car.
Stage 1 remaps in Hertfordshire and beyond
We're based in Ardeley, Hertfordshire, a short drive from Stevenage, Hitchin, Letchworth, Hertford and Welwyn, but we see cars from all over the UK. We've tuned over 5,000 cars to date and have over 300 five-star reviews across Google and Facebook.
You can spread the cost with Klarna or Clearpay, and you can see the full range of ECU remapping and tuning options on our performance tuning page.
Frequently asked questions
What is the difference between Stage 1 and Stage 2?
Stage 1 is software only on a standard car. Stage 2 combines a more advanced map with hardware upgrades such as an intercooler, exhaust or intake, and usually gives bigger gains.
How much bhp does a Stage 1 remap add?
It depends on the engine. Turbo diesels and turbo petrols typically gain somewhere in the region of 10–30%, while non-turbo petrols gain much less. The popular models section above gives typical figures for common BMW, VW Golf and Audi engines, and our power gains check shows the expected figures for your exact car.
Is a Stage 1 remap worth it on a diesel?
For most turbo diesels, yes. The extra low-down torque makes the biggest day-to-day difference, and some drivers see better economy too.
Can a remap be reversed?
Yes, always. We save your original software before writing the new file, so the car can be returned to standard whenever you need it.
Does a remap affect insurance?
You should tell your insurer about any remap. It may affect your premium, and not declaring it could invalidate your cover.
How long does a Stage 1 remap take?
Usually 60–90 minutes including the health check, though it varies by vehicle and ECU.
Will a remap damage my engine?
Not on a healthy engine with a properly developed file. That's why every car gets a health check before it's tuned.
Want to know what your car could gain? Run your reg through our power gains check, or get a free quote and we'll come back to you.
