Beginners Guide to Modifying an MK5 GTI
Want to modify your VW? Start here!
Where do you start? What modifications are out there?
The MK5 GTI is a strong platform to begin with. If you are interested in upgrading to either go faster, sit lower or sound better, this guide will give you some general direction.
Drivetrain Performance (Motor, Exhaust, Intake, transmission)
ECU Tuning: also known as “chipping”, is a way to gain performance by making changes to your cars software to allow it to put out more power. Various stages of tuning give you various levels of power. This is done by something called “flashing” from companies like APR, Unitronic, GIAC, Revo, etc. These tunes can be done in around an hour, you would need to find a software dealer in your area and take your car to their shop. These can be done on completely stock cars and when you decide to modify your car more you can get a re-flash to work with the parts you but on your car. A stage 1 tune could yield up to 50hp without any other modification!
For more info – https://www.golfmk6.com/forums/showthread.php?t=30370
Turboback/Catback Exhaust: An exhaust will free up the airflow out the back of your car increasing performance slightly as well as increasing the sound that your car makes. A turboback exhaust is exactly what it sounds like, a new exhaust system from the turbo back. These can either come with a new high flow catalytic converter or you can get one without a catalytic converter for track use only. A Turboback by itself will give your car more power and a much louder sound, typically most cars need a computer tune as well to gain the most out of the exhaust.
A catback system is from the stock catalytic converter back, this type of system will not gain as much power but will give your car a louder sound.
Motor Mounts: help put more power down and reduce wheel hop. Depending on the mileage, motor mount will help increase the performance of your car by reducing the engine movement. Typically stock motor mounts will begin to deteriorate and you will lose that tight feeling that your car once had. The MK5 GTI has two mounts, an Engine mount and Transmission mount.
Turbo Outlet Pipe: replaces the stock pancake pipe allowing for a 4-5 HP gain. Also known as the “TOP”, this pipe goes from the turbo to the intercooler. The stock pipe is known as the “pancake pipe” because it is very restrictive compared to other aftermarket pieces.
Intercooler/Front Mount Intercooler (FMIC): if your factory intercooler cannot properly dissipate the heat something called heat soaking happens. This means that your factory intercooler cannot cool the incoming air fast enough, which results in hot air being pushed into the motor, Hot air is less dense which = less power. Most cars don’t need a aftermarket intercooler until they are stage 2 and above. The stock intercooler is fine until higher power levels are reached. Aftermarket FMIC have a larger core and piping allowing for better
Intake: When added with tuning, intakes will produce performance gains. They do this by increasing the diameter and flow of the piping allowing for more air to enter the turbo. Some systems have heat shields or actual intake boxes that also help reduce the heating of the intake air, this adds to cool air is denser air which makes more power.
Clutches: a stock clutch is not meant to be able to stand added power. Upgrading it will ensure reliability and longevity to your clutch.
Diverter Valve: A Diverter valve is there to protect your turbo from compressor surge. Compressor surge is when unused air from the intake is redirected backwards when the throttle closes, if the Diverter valve wasn’t there, this air could damage the turbo. Some Stock units will fail allowing for boost leaks which can hurt performance. Replacing the DV is a good maintenance and performance item, it will ensure that your car will hold boost without any issues once you add more power. Most aftermarket unites replace the stock plastic valve with a metal one and can hold up to 30lbs of boost
Lowering Springs: modest 1” to 2” drop, replace stock springs and reuse the stock struts and shocks. This is a great way to lower your car without breaking the bank or making your car too low.
Coilovers: Are exactly what they sound like, Coil springs and shocks in one package. When you buy coilovers you are getting replacement springs and shocks, so it is a complete package allowing for straight forward installation. Coilovers can be height and dampening adjustable. Height adjustable coilovers will be cheaper vs height and dampening adjustable kits.
Bushings: much like mounts, they help solidify the driveline and help put more power down. Stock bushings are typically made out of soft rubber meaning they have a lot of compliance when you are pushing your car hard. Upgrading to a stiffer rubber or polyurethane bushing allows for less movement in the bushing meaning that motion is being transferred to the road or the proper suspension parts, thus increasing the performance and traction of your suspension.
Sway Bar: there are options for the front and rear sway bars, give your car roll stiffness. Also called stabilizer bars because they help stabilize the car in a turn, too much roll hurts traction and can make the car unpredictable. Aftermarket sway bars will help reduce this.
- Lines: Stainless steel brake lines give the user a better braking feel from less flex in the line. Stock brake lines are made out of rubber and can flex when being used hard giving the pedal a squishy feeling.
- Pads: More aggressive brake pads will increase the stopping power of your stock brakes.
- Fluid: High temperature brake fluid for a higher boiling point. This increased braking performance when using your GTI for HPDE’s
Aftermarket: big brake kits have larger rotors, which increase stopping response, along with more clamping power due to more pistons in the caliper. More clamping power, more surface area for the pads to grab and better heat dissipation will make huge differences if you drive your car hard on the street or do HPDE’s