Tunit Performance

Custom Auto Electrics is a recognised Tunit dealer. We can sell and install Tunit products as part of our services.

  • What does the Tunit do? The Tunit improves Power (Kw/hp), Torque and Fuel Economy.
  • How does the Tunit work? Electronic signals that control engine performance & economy are altered to the optimum for each engine by the Tunit software. Signals such as Air mass, accelerator position, fuel injection timing and fuel delivery are measured and from this, a load calculation then delivers new improved signals to optimise the performance and economy.
  • How is the Tunit installed? The Tunit in most cases is provided with Original Manufacturers plugs that and fitting is normally is to a plug on the engine. Tunit Dealers are available able to install or full instructions are provided for self install.
  • Can I install the Tunit myself? The answer is yes. In most circumstances however we always recommend using a Tunit Dealer (such as ourselves) for a professional install and support.
  • Is my vehicle warranty affected? Unlike other modules/chips that connect directly to the injectors and alters/changes the ECU signals to the engine after the ECU has checked and sent what it thinks is safe. The Tunit is upstream allowing the ECU to calculate all safety as it was intended before it is sent to the fuel and induction system uninterrupted.
  • Can I transfer my Tunit to my new vehicle? The Original Tunit has a 3 Year part exchange or in the case of the Advantage II, a Life Time Part exchange. You have the choice of upgrading your Tunit to suit your next vehicle or a full Part Exchange to a New Model. Ask us about these choices.
  • What is the difference between "Tunit", "Chipping" and "Mapping"? The TUNIT is an externally installed computer. CHIPPING involves soldering a new chip into your ECU. MAPPING permanently deletes your existing software on your vehicle and replaces it.
  • Why is Tunit better that other tuning options? The Tunit software has a Unique “load calculation” which allows the Tunit to provide Extra performance when demanded but also reduce fuel the fuel delivered to the engine when required. Tunit has Unprecedented Product and vehicle warranties of 5 Years. Part exchange and upgrade facilities are available to each New Customer. Tunit have supplied Commercial companies, Governments and individuals longer than any other Diesel Tuning company. 
  • Is there a warranty on the Tunit? The Tunit is manufactured with the quality & attention to details that you would expect from expert engineering. The latest Tunit models carry a full 5 year warranty & are guaranteed to work better than any other diesel tuning product available. Tunit Original : 5 year warranty and 1 year Engine/Drivetrain warranty, Tunit Advantage II : 5 year warranty and a 2 year Engine/Drivetrain warranty
  • How long have Tunit been around for? Tunit has been around since 1998 and Tunit's are sold worldwide.
  • How much is the Tunit? The Tunit prices vary depending on which unit suits your vehicle. The Tunit can be purchased as a stand alone unit, or combined with the Power Pedal as a package. The Power Pedal can also be purchased separate and can be used as a stand alone unit.
  • Which Tunit fits my vehicle? Tunit dealers have a huge detailed list of compatible vehicles to make sure you receive the correct unit for you requirements. 


When you need more performance out of your Diesel vehicle, no matter if it is a 4x4 or car, Tunit has a solution for you. Tunit has a unit for most late model Diesel vehicles and also unit for petrol models too.

About the Tunit Module

The Tunit has the ability to increase power and torque by up to 20%. Intercepting the signals between the ECU and the Injection System, the Tunit allows more fuel injection into the cylinders thus producing more torque and power. 

The Tunit has been proven to reduce harmful emissions by up to 27% and improve fuel economy on average by 12% in comparison to other Chip Tuning and Remapping options that doubled dangerous exhaust emissions

Every Tunit is individually programmed to maximise the performance of every diesel engine. When necessary, the Tunit can be easily changed/reprogrammed by a Tunit dealer if required, for example, when more power and torque is needed for towing.

The Tunit is manufactured with the quality & attention to details that you would expect from expert engineering. The latest Tunit models carry a full 5 year warranty & are guaranteed to work better than any other diesel tuning product available.










Tunit Original & Tunit Advantage II (diesel Modules)

These are the Diesel modules. They come in various configurations to suit a large variety of vehicles. A lot of vehicles use the same module with a different harness and programme. The Tunit Original and Advantage II uses the same circuit board and gives the same increases/output. 

The Tunit Originals (V-CR, V-VP and V-PD) all come with a 5 year warranty and 1 year Engine/Drivetrain warranty. The Tunit Advantage II comes with a 5 year warranty and a 2 year Engine/Drivetrain warranty.

Tunit is also available for common rail diesels. For example, the Tunit Common Rail units all are connected upstream from the vehicles ECU (Engine Control Unit) which leaves the ECU to do exactly what it was designed to do and run the vehicle completely. Therefore, it maintains all of its original factory safety settings unlike other injector modules. These injector modules do come up with good increases but are basically a positive and negative on the injector holding it open longer for increase of injector duration. The problem with this is that the ECU no longer knows how much fuel is now in the cylinder and is unable to determine correct atomisation requirements. It also has no control over safety, as it does not know what is happening, it has already sent the information it thinks is happening to the injectors and pump etc.

All new Tunits have a new circuit which has 9 different maps and has been developed to work with new Bosch security controlled ECU's that will shut down vehicles if a non manufacturers part is recognised. It also is a faster processor than it's predecessor.

The Tunit Diesel modules are quite versatile where the end user has 10 settings to choose from via a dial. To further tune this, a dealer has the ability to modify parameters to tune these individually with a tuning harness via a computer. This can be a great advantage if you have had further modifications (ie. oversize exhaust system) after the Tunit has been installed.

Tunit Power Pedal (Can be used with Diesel or Petrol vehicles)

This unit can be used as a stand alone fitment or combined with a Tunit module.

This unit allows you to adjust the feel of the throttle and can help with the lag of some engines. This is highly recommended for XR6 Turbos.

This unit is unique incorporating a Dual Processor for reliability and smooth response. Unlike other units that only have a single processor, if in the unlikely event that the processor fails or has an issue (which has been seen quite a few times before on single processor units) the second processor takes over and eliminates the possibility of being either stuck with either WOT (wide open throttle) or no throttle at all. Also with the design if again in the very unlikely scenario the second processor also fails it reverts back to a standard throttle position, this is not possible with any other module on the market. The other advantages of having dual processors is that the throttle is much smoother in transition with faster processing capability, much like your laptop or computer running multiple processors for speed. With approx. 2500 applications and growing the Power Pedal has the largest range of vehicles of any pedal box on the market. 

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Tunit Optimum (Petrol Module) 

This Tunit is made for petrol vehicles. It simply plugs into your OBD port and you are on your way. 

The Tunit Optimum is the only Petrol Module in the world that tunes via the OBDII port and has a vehicle list of over 14000 vehicles and growing. From a Jackaroo 3.5L to a McLaren 650S the one unit will do them all.  Tunit Optimum Plus is a patented revolutionary chip that is designed for petrol vehicles, naturally aspirated, turbo and super charged, to increase performance by up to 20%. 

The unit is controlled and programmed by a Bluetooth app for Android or iPhone. There are 4 different maps in the unit allowing control of 4 settings Sport+, Sport, Stock and Eco. The unit can be transferred between as many vehicles as you want therefore can be used on different vehicles if the owner sells their vehicle.  The product cannot void warranty and can be removed in seconds leaving no trace of installation . The unit provides real map tuning and is not plugged on sensors. It modifies fuel and ignition timing mapping and is at an optimum after 200kms of driving once it has re-calibrated to an individual vehicle, though a lot of customers experience a noticeable difference straight after installation.