antlee928

Hi,
Ok I have Roger's Xpipe and hi flow cats installed with the standard catback system. My S4 has the smaller (?) rear resonators and the standard rear muffler.

The Xpipe and hi flow cats have certainly freed up more horses and some Sir Issac Newtons, and, the sound is a little richer however still not quite where I want it.

I tried an RMB (not sure whose - it was available free) and had a single oval exit instead of twin pipe exit. I installed and have say that the sound was way too loud and also delivered an incredibly intrusive resonance from about 2000rpm thru to around 2400rpm. So much so that on a short highway trip I arrived back home with a headache and muscle tension in my neck . Suffice to say I quickly changed back to the standard S4 muffler.

So I am guessing a slightly different rear muffler will do the job however I am a little fussy about the sound. Now exhaust note sounds are highly subjective and everyone has a preference of sound. Here's a link that gets close (ish) to the sound I like,


Here are some other links to sounds I like,


So based on the above what advice can the fine folks on Rennlist offer with respect to rear mufflers that you feel may approximate these sounds yet not significantly upset the power and torque curves.

looking forward to the advice.

Cheers
Tony

928mac

How is this one http://youtu.be/9aNzeKnq3ak

The problem is if you will not get the higher pitched euro sound with our larger pipes.

This is a variety
http://youtu.be/eFuvFpRvSfU

dfrhodes

I'm thinking about doing the same thing, however someone posted recently about the S4+Xpipe+RMB=bad resonance problem and showed a custom resonator pipe as a cure. can't find the thread now though..

d

928mac

I am going to find out in a few days because I just bought the used one that was offered last week. I have no cats and small resonators and expect it to be loud, but, I want to try a glass-pac in place of the resonators and see what it sounds like.

Any thoughts

SMTCapeCod

You have good taste, that gloved fist/restrained power tone is tough to hit with the 32V, easier with the 16V in my opinion. I also don't have much affinity for the burble/cackle/track-car wannabe (if it isn't a track car) open exhaust sounds. I've had a couple 32V 928s now, and have had trouble balancing a great sounding idle with a suitably subtle midrange. You might see if you can source/test fit the larger S4 resonators with the RMB, a lot of folks seem pretty happy with that arrangement.

Some of the best exhaust-sound advice that I received a long time ago, was to couple up both interference-type and sound absorption-type performance mufflers. Detriment is that intereference type like flowmaster also provide some impediment to flow. The straight-through absorption mufflers require a large case to take the edge off of the open-exhaust sound at the lower rpm range.
If you put the absorption mufflers near the midpoint of the midpipe there is less likelihood that the packing will burn out, and if you use an interference muffler, putting it near the end of the system will produce the least impact from the backpressure.

I don't get a drone with the current setup on my S3, but it is too loud for me at certain throttle inputs moreso than certain rpms. I'm starting to think my next solution is going to be the x, the 100 cell cats, then straight back to the factory muffler. But I'm not going to beat up the exisiting setup (in sig) until after I verify the cam timing. Actually, ideally I'd just have a big honkin turbo impeller exchanging some of that exhaust noise for comprssor whistle..

I'm still hankering to hear the Roger/928Motorsport LLC system.

rgs944

If you hate open exhaust you are really gunna hate my car.

SMTCapeCod

Not your car, just the racket it currently makes.

J/K. Saw the prior posts of the vid. Couple times.
I like the idle and bet it sounds great over 3K/WOT. But you're right I don't think I'd want to motor around in it on a regular basis in traffic/part throttle situations.

Each his own, I wasn't trying to say how they "should" sound, just expressing my preference- I'm glad you found a solution you like!

rgs944

I know what you meant and I am just kidding around with you. Your right, if it was a daily driver I would not have it so loud. I live in a Muscle car world so I love the reaction when guys around here realize its a Porsche that is making that sound.

c_span

I think part of the problem is sound outside <> sound inside, particularly with a well-insulated and refined car like a 928. To make the exhaust "loud enough" to enjoy inside the cabin quite often means it's pretty shouty to the rest of the world. Mine, GT resonators + RMB, sounds great from the outside (even inside another car following, can hear it loud & clear)... but I need to open the sunroof/window to get the full benefit myself...

Think it's part of the reason why manufacturers are resorting to artificial devices ("tuned" pipes and resonators to make the engine note more prominent in the cabin, a-la Porsche 991) or even artificially generated engine sounds thru the hi-fi (a-la the new F10 M5).

rgs944

A very nice and brand new black Challenger came by the other day while I was walking and I could not hear it at all. It could have been an electric car it was so quite. I don't understand having a nice car like that and not hearing the engine.

Speedtoys

It was me.



Resonance chamber.

WORKS like a BOSS too.

Speedtoys

You couldnt hear it, because you didnt -need- to...yet.

hb4

Need a design for a 2.5" twin pipe version w/X, mid aftermarket mufflers and cats.