Well I did it. Running open header didn't really matter much, the car lost compression on one rotor at the event. It was great fun while it lasted though!

 

I've run it with an open stock exhaust manifold, and it was real damn loud, but it was still livable. It wasnt quite to the ear bleeding point, but I also only redlined it once - it was all I could take. Either way, you should be ok with ear plugs.
Also, NA cars run pretty rich stock. Unless you lean it out somehow, you will have flames.

 

its my vid, they must've moved it

http://videos.streetfire.net/Player....882F&kw=11&p=1

enjoy!

 

ooohh. That sounded sexy.

 

I put the RB header on and just for fun I started the motor. It shook the concrete under the car!!!! Really, Really loud. I have built V8s inthe past and started them with open headers and they were not near as loud as that Rotary.

Open header will not hurt the performance of a rotary as flow is the key on this engine. better in, better out better HP. Not like you need a tuned plenum in the In side of the motor.

 

the vid doesn't show how LOUD it really is............until the very end.........it's painful

but it will affect the performance when the 5th and 6th ports need to open........without the bacpressure they won't open and you will not have powah..........wait.....the presilencer IS where the tube for the 5thand 6th ports connect........so they will still open.........I can't remember

 

If he has an S5 the backpressure is created by the air pump. So if you have no split air pipe bung and just an open hole then you need to plug it up with a bolt or something in the rubber part coming from the intake area. That long stainless steel tube can be taken off and where it attaches is a rubber hose......plug that one. When the smog air pump reaches a certain rpm the 5/6 ports open form the pressure created.

 

my car is an s4, there's a tube that runs from the presilencer to the actuators. I have a block off plate and deleted my airpump.

it feels like ive lost top end when i took off the mufflers, im guessing they aid in building just enough pressure to open the aux. ports.

This past sunday I took the car like this on the 22 freeway, its painfull.

 

I am not sure about the S4 but I think you are missing something that opens the ports. I saw it explained before but bucause I have an S5 I deleted the file from my brain

 

nope, everything is there to operate the aux ports. I deleted the solenoid conrolled valves + housing and airpump. The airpump is there for emissions only on an s4.

http://www.racingbeat.com/resultset....rtNumber=16405 presilencer for s4
http://www.racingbeat.com/resultset....rtNumber=16408 presilencer for s5

edit: fixed links

 

i think i'm the only one that likes the sound of open exhaust.