Lets get that old stock downpipe off and put a nice 76mm stainless steel unit onto the car. Here is a pic of the stock downpipe attached to the car

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1 Hi MMR Fans its that time again, the third issue of the VAG tuning articles. As promised this issue we are going to install the downpipe, decat, and full exhaust system with dyno tests in between to show you the gains. In this article I will also reveal some of the problem areas and irritating features or rather flaws of this GTI which is so raved about. Lets get that old stock downpipe off and put a nice 76mm stainless steel unit onto the car. Here is a pic of the stock downpipe attached to the car

2 Here is what we are going to replace it with

3 Next is the downpipe installed this took us apprximately 35 minutes to remove the stock unit with the first CAT, and install the 76mm custom made downpipe without a CAT.

4 OK the remainder of the pipe leading to the rear split section is also replaced, with a stainless steel section. Here is a pic of the second CAT which we are removing you will see the second lamda sensor just behind it. This is where we need to install a mini CAT which is a mounting adapter with a some CAT material (platinum honeycomb) inside, so as to allow the sensor to still receive a filtered air flow this is done to prevent the engine light from coming on during operation. Lucky for us, we can over-ride this in our ability to change these settings in the ECU s software where a mini CAT cannot be used.

5 Next is a pic of the replaced stainless pipe Note the mini CAT is on the right side of the picture with the sensor screwed into it, and at the rear of the car(left of the picture), you will see we connected the pipe back into the stock system for this test to show the gains of the downpipe and decat with the use of stock software you will be surprised at the result! Well the pipe is installed, and we are ready to check the results on the same dyno, once again also in winter with pretty cool temperatures. Here is a dyno with the following mods done to the car remember this is a STOCK SOFTWARE car, with only hardware changes. Also included in the dyno graphs below are the previous runs with stock setup, then cooler added, and now finally with complete downpipe and decat and rear system 76mm in diameter after this is the remaining section of the pipe (rear section) which we will show you WITH some tuning this is going to be the exciting part, as you will see some SERIOUS gains which will show the potential on 95 octane pump fuel with NO OCTANE BOOSTER specifically setup for a reliable, true street car application.

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7 Notice the torque and power curve it looks like we have lost torque in the lower RPM range what we did was run the car numerous times after the exhaust installation and saw absolutely no improvement at all. We did a throttle recalibration and cleared any DTC codes, did another run this is the result of that run in orange. Conclusion here, if you are running STOCK software with some hardware mods, the only result of an exhaust change is the sound you will hear! Only after software has been done i.e boost increased, will you see any gains with the addition of an exhaust system. OK guys and gals --- here is a small section for what I like to call flaws in this package that VW put together. First some info into where the flaws exist ill concentrate on only one of these flaws for this article and will elaborate further in future articles to come. Although this is a flaw its something which we can fix, and improve the car for owners wanting this. It s the drive by wire system that VW have used (DBW)

8 First gripe its slow, horribly slow! It so slow that when driving in a more aggressive and competitive manner, you have to compensate your driving for the inadequate DBW system, which will land up irritating you to no end. Until I installed the P3cars digital gauge, I was not able to pin point the problem, although I knew that there was a slow reaction with something under the hood. The P3cars gauge revealed it to me, it plugs into your OBD port and displays REALTIME parameters on a digital face which fits snugly into your stock air vent and looks factory fitted without hindering the vents operation! this is another exclusively sold product by TurboDirect, and an absolute beaut of a product one of the features it displays is the throttle position that the THROTTLE is at. (other info is EGT, Boost, Vacuum, Ignition advance, Speed, RPM, Air temp, Coolant temp, etc etc etc) OK here is the operational flaw, I will give you a few examples of this firstly, if you are driving along and suddenly flaw the throttle, depending on the condition of the engine, RPM position, temperature and gear the throttle reacts very slowly, and sometimes when snap changing gears or doing a full throttle gear change, the throttle actually closes to idle position before re-opening again, as it sees RPM limit, and the clutch pedal engaged for a second, and gets confused! This is clearly felt and occurs every time! The pedal will be on the floor and almost a second later the power comes back you can clearly feel the delay in the power, and when watching the P3cars gauge, it becomes clear what the skittish ECU is doing! The other issue is whilst driving in gears above 3 rd, and you slowly apply the throttle (on the highway for example) you will reach % pedal position, and the gauge will read 100% -- gone is the calibration from 70% to 100% pedal application. This is verified in the software map, as I initially thought that the gauge could be mistaken, or reading an incorrect parameter let me explain Here is a pic of the ACTUAL map from the stock ECU which Bosch created for the throttle position OUTPUT to the DBW motor on the butterfly look at the highlighted area and you will see that around the 85% throttle position area, the ECU already tells the throttle to open up 100%, BUT now look at the close area next to the highlighted 100% cells, at 72% pedal position, the ECU is opening the butterfly to 99% at 1750RPM and at 2500RPM the throttle is being opened 98%, and at 5000RPM the ECU is telling opening the butterfly to 95% -- This is done in order to make the car as smooth as possible, but man o man, is it absolutely irritating! There are products that plug onto the throttle pedal which illuminate this irritation, and overcome the slow reaction of the throttle -- Well we have also managed to overcome this by a simple programming change to the ECU s software which is totally undetectable by any diagnostic tools, as opposed to the physical electronic addition mentioned above. Here is a map I have corrected in the software and it has made the car feel a lot more responsive, the throttle reacts much faster and when my pedal is at 70% - the actual position is 70% (or thereabouts!) sure the car is less smooth, but I don t want to drive a floating sofa, I want the car to be crisp, and respond to my every input which it now does!

9 More flaws to follow in the next articles. I hope you enjoyed this article, and I know you are looking forward to the next where you will see the results of some tuning, and software changes once again dyno graphs to show the results. That s it for November Xmas is coming up and TurboDirect will be doing something special for the MMR fans this year make sure you get the next issues of MMR, as without them, you wont be able to qualify for the special surprise I have in store for you all. Later and remember, You enjoy Horsepower, WE OWN IT!!!