Jamie@dundonmotorsports

Wanted to summarize in one spot what's buried in some other threads. The Dundon formula is every engine wants a little something different. A 997.1 3.6L isn't the same as a 997.2RS 3.8L. To that end you will notice that all of our exhausts are slightly different. There's isn't a one size fits all mentality as that isn't how you extract power from engines...

For those that don't know us, our systems are made from 321SS and have a lifetime structural warranty. 304SS and Ti are hard pressed to offer this... Our systems have no drone, and are quiet in the cabin while cruising as we utilize flaps like the factory, and the stock center muffler. Our systems are lighter than factory by the elimination of the heavy side mufflers and our systems make power.


DMS Race Headers, high flow air filters


31whp max gains
27whp peak gains

with Race Headers and high flow air filters (tried with Cobb tune on and off the car made no difference)



Next up was to further improve the airflow by changing to a 4.0RS plenum




And the Dundon 3.8RS Carbon Dual Cone Airbox Dundon 3.8RS Dual Cone Airbox

Then to the dyno, this is all pre tune so you can see what the effect of just the individual components yields

What is shown is
2) runs bone stock 3.8RS
2) runs with our 3.8 Headers and side flap pipes with OEM center, with high flow filter air box
2) runs with the same above except with a 4.0 IM installed

The runs with the Dundon Race header is with a Cobb stage 1 installed. Before when we did not have the air box we checked stock to Cobb-1 and it was smoother but no huge gains. The Total package yields:

40whp over stock @ 7300rpm
40whp over stock at 8400rpm






the difference around 78-7900 is most likely where the 3.8RS is tuned for, as well as this is not a full tune with the 4.0 manifold and air fuel and timing is not fully optimized.

The big dip at 6500 is where the resonance flaps change over and thus cause a huge difference in air flow. We can not change this with the Cobb Pro Tuner software so we have to go with TTFS to tune this out as well as a lot of other things.

If you notice before 6500 the 4.0 is starting to make more power, then the flaps change and the dip is there and then the recovery is a little slower for a few RPMS then it out gains.

Now that we have our dyno up and running we plan to have FJSeattle back to get his car dialed in completely!

AS FAR AS A DISCLAIMER we would not expect the 4.0 plenum to make power unless they have Dundon headers/exhaust and Dual cone airbox. the stock air box restricts before we get to 420whp and it just doesnt want to make more than that no matter what we do. Installing the 4.0 IM means you have to install the lower manifolds as well onto the engine so this is a big job for most and will take a while to do engine in the car or some may just want to pull the engine.

For more information or questions feel free to contact us!
jamie at dundonmotorsports.com
dundonmotorsports.com