The quickest way to add power to the MKV GTI is with an ECU reflash. There are several well reputed companies out there. The three major players here are APR, REVO, and GIAC. The main difference between them is that REVO allows some fine tuning with a small handheld device. You can also switch maps using the same device. APR does not allow fine tuning but you boasts the ability to switch between maps without buying an additional handheld device. I don’t know too much about GIAC. Like APR it does not allow fine tuning by the end user and like REVO, it requires the use of a device to switch maps. Asking “which company is best?” on the forums usually generates endless debate and stupidity. General advice is to find a good dealer that is close to you. I like REVO’s user end tweaking ability and I like APR’s ability to switch maps using the cruise control buttons. You cannot go wrong with any of the major players. I chose APR since they were having a sale at the time of purchase. I also like having the ability to switch flash modes with the cruise control stalk. This wiki page (MKV Wiki) has a nice collection of random internet knowledge.
An ECU flash tweaks the stock engine control maps to make power out of the available parameters. This usually includes, but isn’t limited to changes to the boost levels and the stock timing. As a result, with a simple reflash, you gain around 20 wheel horsepower and 60 ft/lbs of torque. Actual numbers could be more or less, it depends on each car and the dyno. Anyway, during the sale, it cost me 650 dollars to “chip” my car. I set up an appointment and it took a little less than an hour to complete the process. I purchased the Stage I flash with various features such as ECU lockout and other octane modes. The shop I went to was Ingolstadt West. This is a pretty well known shop in the area and they do great work.
Dealers usually tell you that the tune needs a few miles to fully adapt and make full power. I’m not so sure but I think part of that feeling that it “needs to adapt” comes from the way a Stage I tune is delivered. It very closely mirrors the stock feel but with more torque in the midrange. If you don’t punch it when you leave the shop, you’ll be hard pressed to notice a big difference. If you drive normally, you can tell the car feels a bit lighter on it’s feet, but you are not quite sure by how much. Nudging the throttle a little more though reveals a massive torque difference from stock. Speed ramps up quite a bit faster. Definitely an addictive feeling.
To summarize it, an (APR) Stage I flash drives as smoothly as the stock program but has much deeper reserves of power. Passing power, already a strong point in the GTI becomes even better. At every point in the rev range, the reflashed engine is immensely more confident. Lag is almost none existent even with the higher boost level. Stage I peaks at around 19-21 psi.
As with most modifications, there will be a few downsides. Higher boost levels often lead to failure in parts that were designed for stock boost levels. The most common offenders are the diverter valve and the pcv valve. The new revision of the diverter valve is all but bulletproof, though diaphragm versions are prone to ripping. Same story with the pcv valve. Newer revisions are sturdier but older versions tend to leak under higher levels of boost. Some of them failed with stock tuning. If either of these fail, boost pressure will be reduced. Neither is catastrophic but should be tended to as soon as possible. Leaking boost pressure can overwork the turbo over time.
Driving in summer heat and in traffic can also bring up a slightly less responsive throttle. This is present in many turbo cars as heat does the turbo no favors. The more aggressive tune will make it a little more noticeable though. Basically the turbo is not as efficient when ambient air temperatures are up. Not a big deal and certainly not a reason to avoid a reflash. Happens to any car. Hotter air, less power.
Remember also that when reflashing the ECU, we are changing designed engine parameters. These parts were not designed to run at these levels and manufacturers can deny warranty claims based on chipping. The turbo is working harder, the transmission has to cope with more torque, etc. You get the picture. These companies have done their research and I have yet to see any definitive failures as a result of a reflash. Note that this is not a new concept either. Just be aware of the possibilities and pay attention to your engine.
This really is one of the first modifications an owner should look into if they are interested in more power. You just might find that this is all you need. Maybe.
A few reasons:
Cost to gain ratio – Hands down the best ratio of money spent to hp gained. You can throw 600 dollars at intakes and other parts and still not gain 10 whp.
Requires no other changes – A stock car can be reflashed with absolutely no other changes. Just stay on top of your maintenance and your car will last just as long.
Fun factor – The nice increase in torque makes driving that much more fun. Point and squirt. Shift and pass. Oh the joy.
The bottom line is, if you want more power, get the car reflashed. You can then tune the car from there with an intake and other bolt-ons. Nothing short of a turbo swap will gain as much for so little money. I’ve had the APR flash for almost 3 years now and the punch it gives the car still makes me smile.