Ford Focus Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
1,310 Posts
Discussion Starter #1
im extremely tempted, as a first major mod on my zx3, to install an aftermarket cat-back. im primarily concerned with increased power gains and efficiency but a civil amount of noise factors high on my list of determinants. i dont plan on eliminating my cat, but may install shorty headers in the future to get rid of that dent ridden monstrosity of an oem manifold. ive heard several exhaust setups, including bosal, borla, and magnaflow and was really impressed by the latter. however, as naive as it sounds, the quiet tone of the magnaflow has me sketchy about performance. it just seems like all the effort of dampening the noise would end up restricting flow, thereby constraining gains. id bet this goes hand in hand with the popularity of the borla, louder being more free and open and therefore better. i realize the question of 'what exhaust should i get for this, this, and that?' has been handled ad naseum, so dont dismiss this thread as the latest iteration in that debate. im mainly interested in what technologies different setups use to lessen noise and how they affect overall performance and efficiency. thanks
 

·
Registered
Joined
·
362 Posts
Just get the Bosal and be done with it. It has a quiet tone and gives some of the best gains. (even though all the catbacks give about the same gains
) Good Luck!
 

·
Registered
Joined
·
1,310 Posts
Discussion Starter #3
Originally posted by papasmurfZX3:
Just get the Bosal and be done with it. It has a quiet tone and gives some of the best gains. (even though all the catbacks give about the same gains
) Good Luck!
<font size="2" face="Verdana, Arial">thanks for the reply but im less interested in product recommendations then explanations of methods and technologies
 

·
Registered
Joined
·
12,749 Posts
Well in EXTREMELY general terms, you basically have a muffler, resonator, tubing diameter which all play a factor into the sound an exhaust will make. Some do not use resonators, and it's pretty loud. But basically it's all 3 of these in combination, and the size and construction of these.

I can't tell how each of these specifically effects the exhaust note, but just know that it is all dependant on the muffler size and construction (straight through or not), resonator size and construction, and the diameter piping used. I'm sure placement of all these parts plays a pare as well. I mean basically, most of these aftermarket exhausts use resonators, so don't let the sound be your judge of how much power they produce.
 

·
Registered
Joined
·
395 Posts
Maybe a dumb idea, but I have been thinking about making my own exhaust system with Mercedes mufflers. Their late model 4 cyl cars are pretty much silent with 2 1/4" exhaust. Not to mention that they make plenty of power. When was the last time you saw a rip roaring zetec walk a stock 230 benz? Performance does not always mean noise. I would imagine that taking the cordless sawzall to the junkyard would be a pretty inexpensive adventure. The local joe schmoe muffler shop could bend some pipe to fit and weld it together. But Im just a broke student and thats my wack idea. Don't tear me a new one if im completely wrong.
 

·
Registered
Joined
·
2,748 Posts
In purely phyiscal terms. The sound is wasted engergy from the engine. The louder it is, the less efficent it is. The same rule applies for heat. That doesn't really mean jack, though. Any exhaust can make a car less noisy, and most aftermarket exhausts will be more open than stock. A good company can build a muffler that both reduces volume and does not impact performance the same goes for resonators. While there may be a little power loss, most of the exhuast systems have been dynoed around the same gains. There have been several previus post dicussing exhaust power, hope this helps.
Topic: Foci Exhaust...Where's the PROOF?
 

·
Registered
Joined
·
210 Posts
I can tell you that Borla uses a perforated core that has a slight "S" bend to it. I believe that the bend slightly stalls the gasses allowing the preforations and sound absorbing material to do their thing a little more effectively than a straight core. Also the 2 1/2 stainless tubing they use is really thin compaired to most aluminized steel pipe Ive seen. Im guessing thats the reason for the resonance that gets a little louder inside the car at 2800 rpm.
 
1 - 8 of 8 Posts
Top