APR TT RS RSC Catback Exhaust Teaser!

[Arin@APR]

Hey Arin,

I noticed that for your B8 S4 3.0T RSC exhaust, you've advertised a reduction in SPL for the 131 Hz tone when driving at 70 mph.



Then you went on to post the sound spectrum at 70 mph, comparing no muffler vs. stock vs. competitor vs. APR RSC:



Quoting the text on your website:


That's great and all, but I had two follow-on questions (which I hope are being thought about for the TT-RS exhaust):

1) While the 131 Hz tone is reduced by ~8 dB from stock, the ~57 Hz tone is ~6 dB *louder* than stock (or even no muffler)! It's not obvious to me which is a more annoying drone: the 131 Hz tone, or the 57 Hz tone. Depending on which is more noticeable, it looks like the RSC could actually be making it worse compared to stock. Do you disagree?

2) All of the analysis on your site was performed at single speed of 70 mph. I'm sure that this spectrum changes dramatically as a function of vehicle speed (and thus engine speed), and of course load. What sort of analysis / validation do you do to ensure that while things may be improved at 70 mph, that they're not significantly worse at, say, 75 mph?

Thanks!

Marty,

I spoke with engineering for clarification on the questions you asked.

1. Tones at very low frequencies have not been as much of an issue unless the engine is switching displacement. For the Audi, that will not matter until the new 4.0 TFSI is released with cylinder shutoff control. Another factor is the penetration of the tones above the broadband levels. Less penetration means the tones are less noticeable and multiple tones close to each other can actually be more pleasing to the ear. Our designs target the dominant tone around 100 - 130 Hz and usually increase the tones at lower frequencies (typical for resonators with tailpipes). If the tones are not significantly above the broadband levels, it's usually subjectively better.
   
2. Yes, we could make similar plots for other speeds and the frequencies would be different. By choosing 65 or 70 mph for the marketing data, we are showing the speed that people usually cruise at on the highway. It may be worth noting we look at speeds in increments of 5 mph to make sure the sound is ok over a range of speeds and not just one as represented by the marketing data.
   

I hope that information helps! If you have any more questions, I'll do my best to answer!

Thank you!

[Marty]

Marty,

I spoke with engineering for clarification on the questions you asked.

1. Tones at very low frequencies have not been as much of an issue unless the engine is switching displacement. For the Audi, that will not matter until the new 4.0 TFSI is released with cylinder shutoff control. Another factor is the penetration of the tones above the broadband levels. Less penetration means the tones are less noticeable and multiple tones close to each other can actually be more pleasing to the ear. Our designs target the dominant tone around 100 - 130 Hz and usually increase the tones at lower frequencies (typical for resonators with tailpipes). If the tones are not significantly above the broadband levels, it's usually subjectively better.
   
2. Yes, we could make similar plots for other speeds and the frequencies would be different. By choosing 65 or 70 mph for the marketing data, we are showing the speed that people usually cruise at on the highway. It may be worth noting we look at speeds in increments of 5 mph to make sure the sound is ok over a range of speeds and not just one as represented by the marketing data.
   

I hope that information helps! If you have any more questions, I'll do my best to answer!

Thank you!

Thanks Arin! I'm definitely interested in seeing this sort of analysis on the TT-RS exhaust whenever it's available.

[tdi-bart]

hurry apr we need some chip action before winter time! i lost by a car length to a 997 turbo at the end of 4th, granted i did not launch the car and stupid traction control kicked in shifting from 1-2 but still

[Marty]

Any updates?? It's been half a year since the last post!

[Arin@APR]

Any updates?? It's been half a year since the last post!

Production is starting soon.

I'm overly embarrassed it's taken this long.

[fourtunes]

Thanks for the update.

[fjork_duf]

Any updates?? It's been half a year since the last post!

Marty when you get this exhaust we need to have a south bay TT RS meet up. I am with you on the 2k drone. I'm used to it now, but it can get really F'in loud especially going up hill. E.g. Hwy 9. Usually I just leave the engine around 3k rpm to get rid of the noise.

[Marty]

Marty when you get this exhaust we need to have a south bay TT RS meet up. I am with you on the 2k drone. I'm used to it now, but it can get really F'in loud especially going up hill. E.g. Hwy 9. Usually I just leave the engine around 3k rpm to get rid of the noise.

How about you buy it and then I'll come meet up at your area for a demo?

[fourtunes]

If either one beats me to it and gets the exhaust installed first, I'll want a demo for sure.

We should get together for a South Bay TT-RS meet-up either way, though.

[fjork_duf]

How about you buy it and then I'll come meet up at your area for a demo?

Haha... touche. I'm going to spend money on some 18" wheels and autox/track tires first. I'm leaning toward the oem 18" wheels. I haven't seen any posts where anyone has gotten an aftermarket wheel with a stock fit.

The exhaust would be the second upgrade I'd get depending on price.

[joneze93tsi]

Haha... touche. I'm going to spend money on some 18" wheels and autox/track tires first. I'm leaning toward the oem 18" wheels. I haven't seen any posts where anyone has gotten an aftermarket wheel with a stock fit.

The exhaust would be the second upgrade I'd get depending on price.

Did you find a source for the OEM 18's?
I'd love a set as well!

[fjork_duf]

Did you find a source for the OEM 18's?
I'd love a set as well!

They can be obtained from europrice or oemplus. Prices seem to be very close. About $645 per wheel. Which I feel is a bit high, so I'm still shopping for alternatives.

[Marty]

Production is starting soon.

I'm overly embarrassed it's taken this long.

Starting soon, eh? And 3 months later.... ?

[Arin@APR]

Production already started. Waiting game.

[JohnLZ7W]

So will apr or borla ship an exhaust to a customer first?

[Marty]

Production already started. Waiting game.

Sweet! So how about some prototype pics under the car, then?

[Arin@APR]

Sweet! So how about some prototype pics under the car, then?

I'm suposed to do that today, among 5000000 other things. We'll see....

[Arin@APR]

Getting closer.

[jibbed]

Interesting - so you guys are going to support the factory valve system now?

Looks good!

[Arin@APR]

Interesting - so you guys are going to support the factory valve system now?

Looks good!

Nope! No need! RSC handles all of that nicely.

[Marty]

Are those V-band exhaust clamps, not slip-for joints?

[Arin@APR]

They are slip joints.

[tdi-bart]

how is the chip hardware coming along, cause borla is gonna release theirs soon, would that speed things up?

[fjork_duf]

Getting closer.

HOT!

Now we need some more sexy video with that sweet noise! (I've seen the first one)

[Arin@APR]

how is the chip hardware coming along, cause borla is gonna release theirs soon, would that speed things up?

Borla is releasing a chip?


TTRS stuff is almost finished. I'm getting right after waterfest.

[Marty]

Borla is releasing a chip?


TTRS stuff is almost finished. I'm getting right after waterfest.

I hope you guys are willing to share some sound spectrum data to show the difference with this exhaust a low / high load!

And I hope it bolts right up to your Stage 3 downpipe... whenever that's released.

[Arin@APR]

I hope you guys are willing to share some sound spectrum data to show the difference with this exhaust a low / high load!

And I hope it bolts right up to your Stage 3 downpipe... whenever that's released.

I'll see what I can do and yes, it does bolt right up.

[R5T]

Getting closer.

Looks very interesting.
90mm all the way up to the rear axle. ???

[Arin@APR]

Looks very interesting.
90mm all the way up to the rear axle. ???

101 necking down to 76mm and splits to 2x 63mm

[Jman5000]

Any cross applicability for us TT/S folks?

[R5T]

101 necking down to 76mm and splits to 2x 63mm

Is the 101 necking down for the factory OEM turbo or for stage 3. ?

btw, terrible tires under the car.

Dunlop Direzza Sport Z1 Star Spec is the way to go.

[JohnLZ7W]

btw, terrible tires under the car.

Dunlop Direzza Sport Z1 Star Spec is the way to go.

You can't get Star Specs in 19s unfortunately. Had two sets on my mk1 and loved them, would have already bought a set for the RS if they were available.

[Arin@APR]

Is the 101 necking down for the factory OEM turbo or for stage 3.

Factory turbo.

[Marty]

Factory turbo.

Nice teaser pic!

[JohnLZ7W]

There go my plans of not doing another turbo back exhaust. That looks very nice!