I'm very happy with it. In terms of affecting the cars outright performance, as such, I cant really say till I've been on the track, strip or Dyno with it - but Ill eat my hat if the car isn't measurably quicker in all situations. On a fast back road run for 150 miles it felts quicker for sure but in terms of lap times I don’t know how this will translate – Im thinking 4 tenths over a 1 minute track lap?. The DMS has given the car a different dimension and is one less reason not to rush out and upgrade to the next GT3....HIGHLY RECOMMENDED - Im a very satisfied customer! This is not a cheap product and infact the most money I have ever spent on an exhaust set up (and its only headers), for any of my cars ever. That being said its a quality 321SS unit that should last the life of the car, it is a direct fit for 991 GT3RS, 911R and likely the forthcoming 991.2 GT3, so there is a large secondary market if I should sell the car or I can take it with me to my next GT acquisition...and there is also a GT4 set for those who like to row their own gears on track! Thanks Jamie & Charles for your excellent product, your excellent service and all your help in getting these to me. I look forward to your GT3/4/RS exhaust tips next!
~ Mark, Australia: 991 GT3 Race Headers
I have done a couple track days so far and car is definitely faster, I feel the power and torque mainly in the mid range, sounds great too.
~ Alex, Australia: GT4 Race Headers
Video doesn't do it justice you need to hear it in person holy crap does it sound good! I thought my center bypass sounded good but these race headers blows it out of the water in every way. In my opinion these headers are 30% louder than previous setup and the best part zero drone. Listen to the high pitch and the downshifts. I don't know how they do it but thank you Jamie for building such awesome headers One last thing the RS does pull harder.
~ Derek, Taiwan: 991 GT3RS Race Headers
Jamie I am madly in love with my 991 RS with Dundon Race Headers now honestly its transformed. Was out on the track and an instructor friend who had driven it previously drove with the Dundon Race Headers yesterday and got out and said I quote"what have you done to it"
~ Ahmad, UAE: 991 GT3RS Race Headers
Laurent purchased a Dundon Lifetime 321SS Black Muffler to go with his Race Header System and Carbon Dual Cone Intake "At idle, sound is suggestive: not that loud but you feel the engine can tell what he thinks. At low revs and duty, sound is soft. It is even strange how they managed to keep the car that streetable. When you push it harder, sound is more agressive and sound level raise. You have some "pop pops", and others appetizers. At wot...what a glorious sound. It is crystal clear, powerfull and you fell like a professional driver in a race. It is quite impossible not to get emotional and having fun. It is organic / orgasmic. It is pure. wow."
~ Laurent, Reunion Island
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). Driving Impressions: 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
So here is my final review about these Dundon headers: - First of all, these headers are beautiful.... they look so good that I just want to hang them on my wall. A quality product! Comes packaged nicely with a set of K&N filters. - Install by the shop was smooth like a breeze, no fitment issues at all. Took around 2 hours to install - Initial startup: car sounds stock! - Initial drive: Under 3k RPM the car sounds completely stock. Over 3k you could hear something angry lurking waiting to be unleashed, and all the way to redline is described as INSANE, my ears are bleeding!! - Dyno procedure: I was instructed by jamie to follow their dyno steps. Fans at inlets, blocking off radiator heat, monitoring IATs and do a couple of runs. My stock run showed a 344whp baseline with a respectful IAT. After that I drove the car for another 100km and came back 3 days later for a post headers dyno. The post dyno read around 374whp, which showed a massive 30-32whp gain around 5000rpm and a massive 37whp gain around 7500rpm. IMPRESSIVE on a N/A car. The car is otherwise on stock tune with just BMC filters and 98 octane fuel. Car runs smooth with no CEL or any warnings. The sound is exotic! Has a nice and loud bark and the downshifts are just plain brutal. I would like to thank Jamie from DMS for his constant support and for a quality product from DMS.
~ Kareem, Bahrain: GT4 Race Headers