Dundon GT4 Race Headers vs Competitor Race Headers
Would like to make a review of the products as well as the customer service of Jamie in particular.
Summary - High quality products paired with superb customer service - highly recommended!
Just a brief background on the car:
2007 997.1 GT3RS
Car has about 35000 miles and I intend to keep it for a long time to come. Decided to install the harmonic damper, although the harmonic issues are supposed to be less problematic in the 3.6 cars - would like to have peace of mind and if in future I were to consider upping the capacity - there will be less worry.
Ordering / Payment / Delivery process - Jamie is prompt in answering all questions and no pushy at all. Tried to tempt me for the long race headers - but its no go in my country due to the strict regulations here. Jamie kept me updated on the built process of the airbox and shipped both items once the airbox is ready.
Installing the harmonic damper pulley - no issues at all.
Carbon Airbox (dual cone / single inlet) - nicely made and came in a sturdy wooden box (no worry about delivery damage). Noticed no cutout to accommodate the engine compartment fan. After initial installation - upon test closure of the engine lid, realised that the engine compartment fan will interfere with the airbox preventing closure of the engine lid. Messaged Jamie - who told me there were no interference issues with the other 997.1RS he had. He suggested cutting the support spacer on the lower part of the airbox. Tried that - still having issues with interference. Jamie was in the process of ordering an aftermarket low profile fan for me when he realised that there are 2 stock OEM fans. The newer ones are lower in profile and eliminated the interference issue.
He promptly order the new fan and had it shipped to me after he received the fan (fan was not available locally).
After installing the new fan & with the lower spacer height (by 1cm) - there was no interference - but I noticed that the rubber piece that seals the airbox from the intake opening is not flushed with the airbox. Returning to the original spacer height made the seal flush but had a little intereference with the connector of the fan which can be resolved with a file within a few mins (non-consequential part).
Subjectively car feels smoother and more torquey. Having only driven the car in city traffic so far after the installation, I can feel the car being smoother and just generally nicer even in the lower rpm ranges 2.5-4.5k rpm. Haven't have much chances to go beyond that to make even a subjective opinion.
I usually drive the car in the non-sports mode (exhaust valve closed) in city traffic - as I like the intake / mechanical noise over the exhaust noise. In the 2.5k - 4K rpm range - the intake noise is definitely a little louder and more melodious. My wife described it as "the car sounds different in different gears". All in all - it made the car more enjoyable to drive even at mundane speeds. Hopefully the change is even better in the upper rpm ranges. ~ HerShann - Singapore: 997 GT3 Carbon Airbox, Harmonic Damper