Muffler replacement huge horsepower gains!

[Rare Iron]

Cobra owners of a flutter, flock together - or something like that.........

Undy, you ran the 3" inserts over the louvers? No wonder the exhaust was so LOUD!!! This may also have something to do with the "flutter" you guys are talking about, as Undy said he did not have any with the mufflers going with the grain. I recommend going into the louvers (against the grain) for max noise attenuation, but they will flow either way of course. From what I've heard from several customers, they are about 3-4 dBA's louder going over the louvers (or with the grain). There will be a little less drag, but I don't think there is a big trade-off.

Here's a video of Cobrapacks on a Viper....................I know you are Ford guys. Wait til the end, your Ford interest will be greatly redeemed, trust me!

Grab a coffee, beer, or Dr. Pepper - this is about 10 minutes of some VERY neat exhaust analysis. It's also a lesson on how to make a V-10 sound GOOD! Which mufflers sound best??? Enjoy:
http://www.pod9.com/ant/viper/exhaus...k_dyno_day.wmv

-Eric

[undy]

Eric, The flutter occurs when the mufflers are installed as they are intended, for max sound attenuation. When I installed the inserts before, with the louvers being ineffective for max flow and minimal sound attenuation, there was no flutter. This flutter issue is very wide spread, not just your systems (no pot shotz at CC intended here at all, I've always been happy with your stuff and customer support).

You have any thoughts on this flutter issue??

Dave

[FUNFER2]

I had this company make my stainless pipes. The 4" muffler body is, the muffler. No muffler breaking of the welds causing rattling. No glass packing to burn out.
No more cost of ceramic coating and constant polishing. The collector is a venturi with welded "stars" to aid with flow and fluttering. They are very highly polished. The cost is high but, they should last for many years vs. mild steel and re-coating them after a handful of years.

When I receive them, I plan of dyno testing these vs my old side pipes that are from Lone Stars kit. I can't wait to see and test them and find out how much HP/TQ I'll gain.

http://fireflyperformance.com/

[RedBarchetta]

Originally Posted by undy

Eric, The flutter occurs when the mufflers are installed as they are intended, for max sound attenuation. When I installed the inserts before, with the louvers being ineffective for max flow and minimal sound attenuation, there was no flutter. This flutter issue is very wide spread, not just your systems (no pot shotz at CC intended here at all, I've always been happy with your stuff and customer support).

You have any thoughts on this flutter issue??

Dave

Hi Dave. Just a note on the Stainless Specialities mufflers. They do not have a directional louver within them. It's a stainless steel mesh that holds back a ceramic blanket material. I would also suspect that the blanket material gets coated over a duration, as my pipes are louder today than they were when new. WOT will alert every police officer within a 1/2 mile radius (maybe up to a mile if they are down wind.). Ear plugs are mandatory and I have just gotten used to using them all the time now. They also cut down on the wind noise when doing 70-75 on the interstate.

-Dean

[Rare Iron]

Originally Posted by undy

Eric, The flutter occurs when the mufflers are installed as they are intended, for max sound attenuation. When I installed the inserts before, with the louvers being ineffective for max flow and minimal sound attenuation, there was no flutter. This flutter issue is very wide spread, not just your systems (no pot shotz at CC intended here at all, I've always been happy with your stuff and customer support).

You have any thoughts on this flutter issue??

Dave

Dave, I'm not really sure what this can be. I would suspect the louvers in the flowpath are creating this, but if someone running mufflers with smooth perf cores are having the same effect, then that would blow my theory out of the water. I've heard of other sounds described on decel & in-between shifts on manual cars - like backrapping, popping, etc. This is not limited to my mufflers. If you listen to the Z06 Corvette on my website, he is running 3" Powersticks x 20" long, & he accelerates from 30 MPH to 140, then takes his foot off the gas for an extended decel. NO popping or fluttering at all, AND he was not even running tailpipes - the exhaust was dumping under the car! I did not expect it to sound that clean. He was also running into the louvers as suggested.

[undy]

Originally Posted by Rare Iron

Dave, I'm not really sure what this can be. I would suspect the louvers in the flowpath are creating this, but if someone running mufflers with smooth perf cores are having the same effect, then that would blow my theory out of the water. I've heard of other sounds described on decel & in-between shifts on manual cars - like backrapping, popping, etc. This is not limited to my mufflers. If you listen to the Z06 Corvette on my website, he is running 3" Powersticks x 20" long, & he accelerates from 30 MPH to 140, then takes his foot off the gas for an extended decel. NO popping or fluttering at all, AND he was not even running tailpipes - the exhaust was dumping under the car! I did not expect it to sound that clean. He was also running into the louvers as suggested.

All things said, I'm am very pleased with the Cobra Packs.. You really have to be listening hard to pickup on the flutter. The more I drive it the less noticable it's becomes. As I said earlier, from outside the cab you can't hear it.

What I really like about the Cobra Packs are ... the rumble at idle is deeper, more mellow and best of all quieter than the Cobra Sticks were. It still screams at WOT though, as it should. The "under the overpass" melodies are very pleasing too.. .. ya jus' can't resist that throttle blip on entry to let 'em know you've arrived

[DRBB]

Does this thread apply to all cobra sidepipes? I am curious if anyone knows about Unique Motorcars side pipes?