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Thread: Common Mk4 GTI / GLI Mods

  1. #1
    Brings The Ruckus D.Light's Avatar
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    Jan 2008

    Default Common Mk4 GTI / GLI Mods

    The order of these mods is recommended, though everyone decides to go down their own path.

    1. Maintenance before modding- This include changing fluids, spark plugs, filters, timing belt,
    making sure your brakes work etcs… Some cars may need more maintenance than others, but
    it’s never a good idea to start modding a car that has not been properly maintained.

    2. Catch Can- A catch can is a great preventative mod that will reduce the amount of carbon build
    up in your engine. Our PCV systems are a known problem, and carbon buildup becomes a big
    issue that reduces power in our cars. Although a catch can will not completely fix the issue, it
    will definitely help. Pairing one with the occasional sea-foaming will help keep your valves clean
    and carbon free.

    3. Downpipe (DP) and ecu tune- The reasons I put these two categories together is because they
    go hand in hand. I will explain each individually later on. The stock DP on the mkiv 1.8t is very
    restrictive and sucks a lot of potential from the engine. Adding a larger downpipe (usually 2.5-
    3inchs) will allow your engine to breathe like never before. But since the engine is tuned to use
    a small restrictive DP, adding a DP alone will not add much gains; it actually could cause your car
    to run badly. An ECU tune will allow the engine to properly use its new DP and give you the most
    power gains for your buck.

    4. ECU tune (more detailed)- Every car has an ECU (engine control unit) which is basically a
    computer that controls many different aspects of the engine. VW engines have a tendency
    to be underpowered from the factory, and the easiest way to fix it is to tune the car. There
    are 5 major tuning companies: APR, UNItronic, REVO, GIAC, and Gonzo. Most people choose
    whichever is closest to them, and there is a lot of debate as to which is best. APR has the
    reputation of having a good balance between power and reliability, whereas UNI and GIAC
    are more aggressive. REVO has mixed reviews, some love it, some hate it. Some REVO tuned
    cars run lean which causes engine problems. Gonzo is a new tuner that has recently come out
    and for the most part has had great reviews, but being a new tuner, his tunes have not been
    time tested for reliability yet.
    Each tuner has different stages of tuning. Stg 1 is just an ECU tune, no other modding is
    required. Stg 2 requires a downpipe, and an intake is recommended. Stg 3 is a big turbo(BT) file,
    which involves changing the turbo and requires a lot of engine work.

    5. Exhaust- As previously mentioned, the stock DP is restricting, and changing it yields big gains.
    The downpipe is the part of the exhaust that bolts up directly to the turbo. A stock downpipe
    will have a Catalytic Converter (Cat) on it. An aftermarket DP will either come with a high flow
    cat, or catless. Most people make their decision on going catless or not based on state laws and
    being able to pass emissions/inspections. Performance wise, there is almost no difference. The
    part of the exhaust that attaches to the DP is called the catback. It is not necessary to change
    unless you go BT. That being said, a lot of people enjoy upgrading the stock catback so that their
    car produces a nicer/louder sound.

    6. Intake- People have different views on how helpful an intake is for the engine, but general
    census seems to agree that it’s not very useful. It adds a nice noise, but does not do much for
    performance. There are plenty of intakes out there, but essentially they are filters on a stick.
    Buying a 300$ intake vs buying a 40$ pod filter and sticking it to the end of your MAF will
    produce more or less the same results.

    7. DV/BOV- After getting a tune, it is recommended to upgrade the factory Diverter Valve (DV).
    The diverter valve allows the excess pressure caused by the turbo to be released or recirculated
    in order to prevent unnecessary damage to the turbo/engine. Another option is a Blow Of Valve
    (BOV) which causes excess pressure to be vented to the atmosphere and adds a Pshh sound
    every time you take your foot off the throttle (some love it, some hate it). Some BOV can be
    problematic for the MKIV, so if you decide to buy one, you have to make sure it closes at idle.
    The HKS SSQV BOV has been proven to work well with our cars.

    8. Intercooler- Our stock intercooler is small, and may not be efficient enough to cool the air
    of a tuned car. If you are stock, then upgrading the intercooler might actually make you lose
    performance. Since aftermarket intercoolers have a larger core than stock, it takes more boost
    pressure to fill it up, resulting in possible turbo lag if the car is not tuned. But if you have a tune,
    it will be helpful in reducing heat soak. These intercoolers are also known to heat soak on an untuned
    vehicle as well.

    9. Water/Meth kit (W/M)- Cools down your engine so it can run more efficiently. It can also help
    clean the valves that are notorious for caking on carbon. W/M kits allow you to run more
    aggressive timing, which gives you more power. But if your car is tuned to run a W/M kit, then
    you have to be certain that the W/M tank never runs out. It could cause major damage to the
    engine if a car tuned for W/M does not use it.

    10. Suspension- The stock suspension on our cars is mediocre at best, and upgrading the suspension
    is usually one of the first mods that is recommended. There are multiple ways to do this. If
    you’re looking for a slight drop with improved handling and close to stock ride comfort, then
    a shock and strut combo would probably be your best choice. The problem with this is that
    you cannot raise or lower your car how you like, it is a set drop, and if you ever want to go
    lower in the future (which 99% of people always do) then you will have to buy another type of
    suspension. The most used suspension upgrade is coilovers. Coilovers allow you to raise and
    lower your car to the height you desire. They have a large price range, starting from around
    400$ to being over 2K$. The difference will be ride comfort, adjustability, reliability, and
    performance. The last option is airbags. These will allow you to go subframe to the ground LOW,
    and with the push of a button be back at stock height. People who have bags are usually more
    about form than function, so if you plan on auto-Xing or tracking your car often, coilovers are
    probably a better choice. That being said, Bags do improve handling over stock.

    Misc Suspension parts- The shock and struts are only part of the suspension, but there are
    many more things you can do to improve handling and grip. Getting a thicker front and rear
    swaybar will reduce understeer and allow your car to stick to the ground more. Most people
    who are performance oriented upgrade the swaybars. On the other hand, many who have
    Bags remove them completely because it prevents them from going as low as they want to be.
    Another upgrade is the dogbone mount. This will cause slightly more vibrations in the cabin,
    but will allow you to have much better grip and much less wheelhop. Upgrading the Suspension
    bushings will also improve handling, but will cause more vibrations in the cabin.


    I'm gonna add to this weekly if not daily, but this will be a good starting spot for most new members
    Last edited by boostedJTi; 03-14-2013 at 07:51 AM.

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  3. #2
    Banned User
    Teh Chr!s's Avatar
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    Default Re: Common Mkiv Gti Mods

    04 TR .:R32 1of500 ( Stage 4 Supercharged )
    04 BMP .:GLI (.:R32 Swapped)
    08 Audi A3 3.2VR6 Quattro ( Daily Beater )

  4. #3
    boostedJTi's Avatar
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    Default Re: Common Mkiv Gti Mods

    Bit of food for thought.

    Stock cars require a .032" gap on the spark plugs

    Chipped cars should go 1 heat range cooler and gap to .028"
    02 GTi - Totaled
    98 Golf 4 door - Sold
    93 Corrado SLC - Sold
    00 Passat GLS - DD
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    Hidden Content Originally Posted by Thalo Hidden Content
    Can't get your loose stick into top gear, eh?

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  6. #4
    Banned User
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    Default Re: Common Mkiv Gti Mods

    Quote Originally Posted by boostedJTi View Post
    Bit of food for thought.

    Stock cars require a .032" gap on the spark plugs

    Chipped cars should go 1 heat range cooler and gap to .028"
    good point .... if u donot gap them to the right spec ..... if ur chipped and dont gap them to .028 u will get misfires at full throttle and it will run crappy
    04 TR .:R32 1of500 ( Stage 4 Supercharged )
    04 BMP .:GLI (.:R32 Swapped)
    08 Audi A3 3.2VR6 Quattro ( Daily Beater )

  7. #5
    Banned User
    Teh Chr!s's Avatar
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    Default Re: Common Mk4 GTI / GLI Mods

    Another Little Tidbit Of Info
    -1.8T MAF Size Is 2.75" So If U Dont Wanna Drop Alot Of $ On A Intake Just Get A K&N Filter With A 2.75" Opening And Clamp It On The End Of The MAF.

    Side Note
    What Happend To Updating This Weekly/Daily D .... Slacker
    04 TR .:R32 1of500 ( Stage 4 Supercharged )
    04 BMP .:GLI (.:R32 Swapped)
    08 Audi A3 3.2VR6 Quattro ( Daily Beater )

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