Hey all, I am putting a new exhuast on my S4 base pretty soon (Mods are new rebuild, intake, RB RR header that will be collected, S5 intake manifold, ALuminum Flywheel and some other stuff). But with my Road Race header, which will be collected to 2.5in piping and will be using A Borla XR-1 Sportsman as my muffler, might have a presilencer on there as well. But I was wonering if there would be any benifits of using a larger tip and the end of the muffler, or using a can type of muffler like the N1. Will these just be louder?

 

i think they would be deeper, gotta love the 4 1/2 inch apexi tips

 

here is a pic of my dueals. (im always showing off)

 

You will want to put one of the RB Presilencer's on, so that the 5th and 6th ports still open up, or else you will have to wire them open, and sacrifice low end power.

 

where's silverrotor when you need him?

he has a NICE exhaust setup.. and some other type of port actuator setup that is really beautiful..

ive got some things to ask him if he pops up in this thread..

 

All a large tips are for is looks and maybe some kind of a sound difference, but I can't emagine that it would make it sound better since it would just resonate a little bit. That is my 1 cent.

 

I don't like the looks of them.
You don't need a presilencer to open the aux ports, that pipe is just there to pump air into the cat.

 

rotary>piston,

you talking about s5s or s4s? i was told they have different actuation methods..

 

No, but you do need back pressure to open the six ports on an S5 intake. And the presilencer gives you more back pressure. And that pipe is not for the 5th and 6th ports it is for emmisions.

 

S4's use vacume and S5's use back pressure.

 

woah.. i thought it was the other way around if anything..

 

Ooops

 

You are incorrect. You dont need backpressure from the exhaust to open the 5th and 6th ports on s5 cars. The air pump is what opens them on s5 cars. The s4 cars are what use the back pressure from the exhaust to open the ports.

 

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can you change the way the ports open on an s4? like switching to the air pump?

 

Mhm

 

And don't worry about Aux ports, I will be using the airpump via a RMP switch. And this will be a single passenger side exit. Does anyknow else have input?