The puzzling thing to me is this table from Fabspeed. It implies that at full throttle the sound level is the same between a stock muffler and their muffler bypass!?

I'm assuming the sound frequency is different so that the bypassed car is easier to hear?

 

I have the fabspeed muffler bypass on my turbo.In the morning when it's quiet in the neighborhood I always regret them.They are loud to the point of annoying.My wife says she can hear me for 5 minutes after I leave.But once I get out on the country road I drive to the office.I love them.

 

Pete,

To get Waldo ready for sale, I took off the bypasses and put my old B&B mufflers on. The car is soooo quiet that even my wife hated it. I don't get the fabspeed chart. Its true that as the turbos spool up, they add their own muffling, but the same db level as stock mufflers? No way.

With a helmet on, you may still not get the required exhaust sound. Scott Mellor runs Cat bypasses and mufflers for everyday, and then replaces the mufflers with muffler bypasses for the track. Now *there* is a racket!

 

I think the Fabspeed chart has a typo... I says "muffler bypass Sport Exhaust" which doesn't make sense. I think that chart is for their sport exhaust, not for the bypass...

Anyway, I will try it. Simple and inexpensive enough... I'll report back next Thursday evening

 

As a reference point, here is some in-car footage from July 27th. You can barely hear the motor.

Movie of Turbo

Now, some in-car footage from my Elise which is dedicated to track duty (now that is some nice engine RPM feedback!).

Movie of Elise

Now I can't wait to see what the Fabspeed muffler bypass pipes will sound like. I'll post an in-car movie for comparison.

 

Pstoppani

Where is the 1st track at, I know the 2nd is PIR. The Lotus has a red light at center tach. that comes on, no rev limiter ?

The sound difference wouldn't have anything to do with Lotus weighing what, 40% less and the engine about, 2-3' hehind you skull would it. Only kidding, pretty dramitic difference!!

 

Pacific Raceways in Auburn, WA.

The Elise has both a shift light and a limiter (which is variable, hence the need for the light).

The main reason the Elise sounds that way is that I've installed an aftermarket exhaust; hence the search for something similar for the TT

The TT's main sound deadener (with the windows open; the case I'm most interested in), are the turbos, which are amazingly effective mufflers.

I have a twin turbo New Beetle that has the same issue but it now has an automatic muffler bypass valve that kicks in at 3500 RPM so it is now easy to hear. That would be the ideal setup for the TT but I don't see anyone making such a gizmo. If I like the bypass I may look into having a manual bypass made so for track I can open her up but for normal driving keep it closed.

 

OK here is my take:
I have FVD cat bypasses and tech EFX mufflers. Nice and growly, performs super no resonance.
Downside is every 2 years I have to do a cat shuffle for smog.
At the track, particularly the streets of Willow, I would hit the rev limiter if I was not paying attention.
I also have a set of muffler bypasses that I put on now when I go to the track. The downside is, by the time I get home, I am ready to stick ice-picks in my ears to make the drone stop.

 

Fabspeed muffler bypass pipes installed... oh yeah, they sound GOOOOOOD....

Final auditory testing awaits track time Thursday...

Thanks for the tips and encouragement to try this pipes

 

im using the cargraphic muffers for both street&track.
I think this is a nice workable compromise as they do sound a bit like a bypass pipes on startup, they have a bit of a growl, and it seems you can slightly hear the turbos spool.
I dont know how these compare to fabspeed mufflers, but im so much happier compared to the stock mufflers. As said above, it is hard to hear the muffers when you are in the car and there is noise at the track, but many people have commented that my car sounds really cool with these mufflers and yet, not so loud that the neighborhood wants to put a hit on me.

 

Can you hear the CarGraphic muffler in the car at the track?

So far, the muffler bypass pipes are a bit annoying around town... they drone/resonate above 2500 RPM at part throttle (steady state driving). I may have to resolve myself to using them only for track days...

 

pstoppani: If you want to get rid of them let me know. I need to buy some to put on 'Waldo'. Yes there will be another Arena Red 993TT in the area.

 

Lots of people report the droning with the bypasses, but lots of others (including me) never found that to be true. I wish I could understand why there are such diverse opinions. Waldo has stock cats and (had) stock turbos, but a high performance ECU. Anybody have any thoughts on this split in opinions?

 

I believe the difference is in the people, not the cars. I've driven cars that people say don't drone, but they did to me. I've come to know and accept that I'm more sensitive to low frequencies than others.

 

I didn't realize that Waldo moved to Seattle! Cool