I have been following the threads about the Top Secret Ti muffler. It saves 45lbs off the stock exhaust, but raises some questions about street usage:

1) Is it necessary for a lightweight muffler to be loud? Do manufacturers assume that aftermarket exhausts should set off car alarms or is it a real engineering problem? I would expect that proper Ti baffling inside a Ti muffler would also be fairly light (although I know nothing about exhausts), but the Amuse is reputed to be nearly straight-thru.

2) How do silencers work? Are they enough of a flow constriction to hurt performance? Is there such a thing as a universal silencer, if the manufacturer doesn't supply one?

It sounds like the best balance between noise, power and weight is the Mugen exhaust. Is that the general consensus?

Thanks,
Tanq

 

By nature the pulses of exhaust gas (and the subsequent sound waves/pressure) of a piston engine are quite loud. By design, a muffler reduces the effects of these waves and inevitbly present a restriction to power at high RPM (high exhaust flow rates). While I'm sure there is a science to this that goes beyond what is "popular," the rule of thumb is quieter=more restriction=less power output. It's pretty much that simple.

An all-titanium construction would be expensive and heavy- while the muffler case could be all Ti, I doubt that all the batting internally could be- that's usually fiberglass. Maybe Ti fibers...?

 

[QUOTE]Originally posted by Tanqueray
[B]... but the Amuse is reputed to be nearly straight-thru.

.. How do silencers work?

 

There's also the fact to think of that Titanium isn't as good as some other materials when there are high temperatures, or lots of temperature changes. I'm pretty sure the front section of the Mugen exhaust is steel for this reason.

-Brian.

 

Chris, any comment on the Mugen? Is it a twin-loop like stock and like other Mugen mufflers? Is there any consensus on power gains?

I prefer something quiter (or something that can be quited, for the street) but don't care for looks or something that won't save weight or power.

 

Confused by this statement what temperature changes are you referring to? Air temp? Exhaust Temp?

 

It is straight through design and not a twin loop. It weighs much less than the stock cat-back. I dynoed less with the Spoon exhaust compared to the Mugen I had in place, but used a different dyno. The Mugen is about the same loudness as stock, imo, perhaps only a little louder.

 

[QUOTE]Originally posted by marcucci
[B]Chris, any comment on the Mugen?

 

Can anyone comment on silencers? I wouldn't mind having a loud exhaust at the track as long as I can lower the volume driving around town.

 

With the silencer for the spoon exhaust, from inside the car, it's still really loud in the low rev range. It's fairly quiet outside, just depends on how much you torque the bolt that keeps the silencer in place.

I think that the silencer for the J's racing exhaust fits the Amuse, at least that's what I remember reading in another thread. Not sure if this will fit the Top Secret.

The silencer for the spoon and I'm guessing for the J's and Amuse is tapered at the end that goes farthest into the exhaust pipe. So it creates a cylindrical air pocket between the exhaust pipe and the silencer, I'm not sure but I think the sound waves are broken up and kept within the pipe, which explains why it's still loud within the car.