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We're very happy and humbled by the response we've received from the forum members on our development work for the GT4 so far. We've finished up the development and production prototypes. Just tested them on the car this morning.
Here's the results on a stock car, bolt on, no tune.
Our dyno read the stock car at 330.8 whp at 7400, Porsche rates the car at 385bhp at 7400, this is 14.1% loss with our Dynapack 4000 hub dyno running the car in Rolling Road mode using the factory PIWIS tools.
Using this Conversion the headers alone get us to
426BHP
For those that want a bit more we offer a Cobb Accessport with a Dundon Motorsports Pro Tune tailored to the Race Headers.
Dundon GT4 Race Headers with Dundon Pro Tune
Dundon GT4 Race Headers, Dundon Pro Tune. 377.1 WHP
The Headers are 18 Ga 321SS. We keep stressing this as the quality of the materials matters. It dictates fitment, it dictates the quality of the welds and the ability of the system to withstand the abuse a car like the GT4 can dish out. This makes our systems cost more than our competitors as 321 is typically 2x the cost of 304SS (what most others stainless systems are made with), but it's important to us to use great materials. We believe in it so much that we offer a lifetime structural warranty to the original owner of our systems.
Design:
The design of our headers is unlike any other on the market, and was specifically created for the GT4, not just to fit a 981 Cayman, but specifically for the 3.8L engine in the GT4. When we make headers for the rest of the Cayman family they will specifically designed for them as well, each engine requires a different design to extract the most from it!
Fitment with factory PSE:
The Dundon Race headers are designed as a direct replacement to the factory system and will bolt right up to the factory sport exhaust, so you retain your valves and ability to quiet the car down for "dinner date duty".
Sound:
Very much a dual personality system. With your foot out of the throttle very livable, talk on the phone in the car etc. PSE button on and foot in it, and get this!
To keep the CEL off while using this racing and offroad use exhaust, we have improved our post cat O2 bung defouler so that it is off 99% of the time. We've been testing with 991 GT3RS with very finicky programming and it's been working like a charm.
Plenum/TB:
We ran a popular plenum and 82mm TB on our headers and our tune and found no measurable improvements even at high rpm. This is good news to some as it means the power improvements are easily achieved with just headers and a tune or even headers alone. We do believe there is more power available through work on the intake/plenum and we will be pursuing this as a Stage 3 package. Work is on going fitting porsche factory parts as a modification.
Street System:
Catted system development is already underway and we will putting together a prototype for testing in the next 2-3 weeks. We need to finish the 991 GT3 catted system first and then back to the GT4 catted.
Dundon Race Header Pricing and ETA:
We sold out the initial group buy and as we finish the first batch of 20pcs, we're already getting materials in stock for the 2nd batch of 20. We're looking at 6-8 weeks to have the next 20 finished. We'll push to do it faster, but this is realistic looking at the last 20 pcs.
Retail Pricing for them is $4250.00 Rennlist Pricing is $3950.00
Ground shipping in the US is free
Tune Pricing:
The Cobb Accessport is a very convenient and stable method for tuning a modern vehicle. It has the ability to store tuned and stock files, log engine parameters and read/clear engine fault codes. The price of the Cobb Accessport is for the device and some generic off the shelf tunes. The OTS tunes add some power, but not near as much as our custom developed Pro Tune.
Cobb Acessport: $1295
Dundon Pro Tune for Race Headers: $495
Package Pricing:
We'll offer a further discount for those that order the headers, Cobb AP and Dundon Pro Tune at the same time.
Total Package Price: $5590 (savings of $250)
Please email Jamie@dundonmotorsports dot com and we will send a paypal invoice for a deposit
I saw the other Rennlist thread with your header mock-up, but do you have pictures of the finished product to share? Curious about fit & finish, flange thickness, and how the headers compare to other designs on the market.
Thanks for the help.
Results look great. Been waiting on these for awhile now and wish I could buy them. Unfortunately going through a damn divorce now so I have to wait. Can't wait to hear people's impressions of them. Congrats
First of all, thanks Jamie and the Dundon crew for working to provide options to the GT4 community. I've followed several threads here at on Obsessed Garage with your work on the GT3 (specifically Matt's car) with great interest.
Two questions I'm hoping you can help with.
1. Here in CA, we're hampered with sh*tty 91 octane. Can I assume that your testing is all done with 93 octane?
2. If so, I'm guessing we'll anticipate slightly smaller gains on 91 octane but shouldn't anticipate any problems, correct?
Thanks in advance. To be honest, I'm likely not making these kinds of changes while my car is under warranty (I'm a bit of a wuss that way) but I did headers on my old Carrera S and loved the results. I anticipate doing that with the GT4 down the road.
You, my friend, win the internet today. Had me rolling...
Originally Posted by Alan C.
email sent
Thanks Alan, we'll get them going as fast as we can!
Originally Posted by Buteo
No ****. I get on here and keep finding ways to spend money.
Dundon- very tempting!
Do it!
Originally Posted by FJSeattle
Good work guys.
Originally Posted by Mech33
Yeah, really impressive results!
Thanks guys!
Originally Posted by belfo
I saw the other Rennlist thread with your header mock-up, but do you have pictures of the finished product to share? Curious about fit & finish, flange thickness, and how the headers compare to other designs on the market.
Thanks for the help.
We guarantee fitment on the car, this is one of the reasons we use 321SS, and if you'd like some references to other customers of Dundon exhausts for fitment, installation etc, happy to provide them. We've spent a lot of time and R&D on the design and it is quite unique, this is what provides the benefit. We know the design will get out to our competition at some point, but we're trying to delay that for as long as possible. We're small and don't have the resources of some of the big players... The fitment is great and all the under body panels fit with no modification required.
Originally Posted by CarAholic
Results look great. Been waiting on these for awhile now and wish I could buy them. Unfortunately going through a damn divorce now so I have to wait. Can't wait to hear people's impressions of them. Congrats
Thanks, hope you get to keep the GT4!
Originally Posted by Da Hapa
First of all, thanks Jamie and the Dundon crew for working to provide options to the GT4 community. I've followed several threads here at on Obsessed Garage with your work on the GT3 (specifically Matt's car) with great interest.
Two questions I'm hoping you can help with.
1. Here in CA, we're hampered with sh*tty 91 octane. Can I assume that your testing is all done with 93 octane?
2. If so, I'm guessing we'll anticipate slightly smaller gains on 91 octane but shouldn't anticipate any problems, correct?
We ran the testing on Washington State 92 Octane with 10% ethanol. The improvement % would be the same as your car is running on 91 octane to start with. The absolute numbers may be slightly different but the gains I would expect to be similar. With the tune I would also expect similar gains as we did most of the work managing airflow, and only moved the ignition timing based on the new torque peak and trough positions. Without the tune the car will likely be able to hit the stock ignition targets more of the time as the cylinders are filling more efficiently with the race headers than with the stock system.
Originally Posted by Tik
Jamie, will you offer a GB on the street system as well?
Absolutely, we offer intro pricing on all of our products when we roll them out!
How about an 100 octane tune?
There's a Sunoco station in Nashua that sells 260 GT from the pump.
Modern Porsche's have ignition targets and a complicated set of formulas that allow them to reach the targets or not (air temps, coolant temps, load, knock all play a part). If you run 100 octane on the current tune, the car will be unlikely to see knock so will not pull timing based on this, it will still calculate timing based off the other inputs.
We can make a tune for 100octane and you can switch back and forth when the car has 100 octane in the tank you'd just have to make sure it is really running on 100 octane, not a mix of 93 and 100 for example...
This would be something to arrange with us separately if you're interested...
Awesome opportunity for GT4 owners to jump on these headers for a great introductory price.
Hopefully we get the chance to setup some local GT4s with your headers sooner than later. We'd love to do some independent dyno testing for the community as well.
08-17-2016, 11:37 PM
Dundon GT4/Spyder Race Header Rennlist Pricing
