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I must admit that I had been dreading reaching 100,000 miles, especially as it has coincided with me becoming an OAP, at least officially if not in mind. The fear was that it would be the beginning of the end but in fact it's the beginning of yet another new era. Generally the car feels the same to drive as it did after 50,000 miles - Gosh, that now looks such a small number when written! For those who don't know, she's a Mk5 GTI K03 built in July 2005 and owned by myself from new.
I've never created a build thread on the forum and quite honestly it would be very tedious and longwinded to do so retrospectively. I've been running Revo Stage 2 for a while and when a Forge Twintake was installed JKM needed to reduce the Boost setting a notch to compensate for my OEM fuel pump. A dyno day session at JKM this February showed a drop in bhp to around 244 from a maximum of 269 in 2011 and it was thought that, subject to logging and investigation, perhaps the valves might need replacing. Fortunately, this was not the case and Jim at JKM took the opportunity to inspect the stems etc and they were found to be surprisingly clean which is unexpected for a high mileage 2.0T FSI engine. Having a catch tank probably helps more than anticipated, as does changing the oil every 10,000 miles regardless of Volkswagen's longer service intervals. I also change the plugs every 20,000 miles. All these actions have been recommended to me by professionals as being a good maintenance practice for performance modified cars.
JKM's investigation diagnosed that the OEM fuel pump was occasionally struggling although I hadn't experienced any dreaded fuel cuts but just sometimes a lag in response when pushing on hard. My choices were an OEM replacement but that wouldn't have solved the problem; Autotech internals fitted to my existing pump; Or an APR High Pressure Fuel Pump built for purpose and guaranteed to handle whatever is thrown at it. The APR is by far the most expensive option but I had to put my money where my mouth has always been on the subject in the forum. Installing the APR also allowed the Revo Boost setting to go back up a notch and my car return from 'Stage 1.5' to Stage 2.
Also, a new MAF was needed - The first since the car was built. So my 100,000 mile oil service at JKM also resulted in the APR HPFP, new Cam Follower (although not needed yet), new MAF, new replacement Forge Twintake filters, new fuel filter, and new NGK Iridium spark plugs.
I've driven 780 miles this week and she feels fresh and invigorated - So do I !!
Something I have learnt from modifying my car is to always leave 'headroom' tolerance rather than push the performance envelope to the max. Max power is undoubtedly fun but it potentially sacrifices reliability and longevity and can get even more expensive. Driveability is what I have always saught and that includes good handling and strong braking. My Mk5 GTI is very tactile and fun. I now feel very confident about the next 100,000 miles!
Credit where credit is due: