Too Loud

[70ptta]

Whats up guys. Right now I have a 3" exhaust out the side in front of rear tire on my challenger and it is way to loud. I almost got a ticket for them being to loud but he let me slide this time. It has thrush mufflers but I cant find the part number on them to see which model is it. I think its their 2 chamber mufflers. Does anyone know where these mufflers have the part number or how to tell them apart? Also whats a good muffler that wont be to loud but wont hurt performance and sound good? Thanks

[70bird]

It is the 3" pipe that makes it so loud. Changing muffs probably won't help very much. If you find a muff that will tone it down some you will probably increase back pressure at the same time.
A good 2 1/2" system will be quieter for the street, and will support up to 550ish HP. Tail pipes will help decrease the noise. Especially inside the car.

[70ptta]

What about 3 inch to the muffler and 2.5 out? The motor is close to 500 fly wheel hp

[Blown353]

3" to the mufflers and 2.5" out is just fine.

Dropping 1/2" in tubing diameter after the mufflers is usually a good idea; the exhaust gas has shed a lot of heat by the time it exits the mufflers and has thus decreased in volume (PV = nRT); dropping 1/2" in diameter after the mufflers using a tapered transition (like the Flowmaster venturi reducers) keeps the exhaust velocity up by making the system act like a convergent duct. Keeping the velocity up helps scavenging in the end.

As far as keeping it quiet, tailpipes help the perceived volume level. To have the car quiet and not have an HP robbing exhaust requires the largest case mufflers you can fit under the car, preferably of the straight-through style design-- i.e. Dynomax Ultraflow, Borla XR-1, Magnaflow, etc.

My car makes about 650hp at the rear wheels an I run the largest case 3" Magnaflows I can fit on it; the exhaust note is fairly quiet at idle and low-load conditions, but it's pretty loud when I'm on it hard.

[70ptta]

I really want to keep the pipes out the side so Ill try just down sizing the outlet tube 1/2 an inch and see what that does.

[funbnme]

Quick Hijack....

Would putting a reducer at the end of the pipes give you any reduction in sound?

I've got a 68 Camaro with 3" exhaust and would like to quiet it down a bit. If I cut off the last foot and put a reducer there, the have the pipe come out the back of the car, do you think that would help quiet it down at all?

[sporter]

If you want 3" all the way and quiet you'll have to go with a pretty big muffler. We put Dynomax 17770's on my son's '79 Z28 and they were a huge improvement over the Flowmasters. With the Dynomax's you could carry on a normal conversation in the car at highway speed, whereas with the flowmasters you had to shout to be heard. Be warned, they are huge and you will need some ground clearance to use them. They are 5.5" by 11" by 20" but are a true 3" turbo design.

[tiznodd]

I had a similar problem with my 3.5" system. I made 3 changes, all of which made a significant difference. The most pronounced difference was changing the mufflers. I went from a 2 chamber flowmaster to the Magnaflow race series which is a straight-through muffler. The change was huge. Also, adding tailpipes makes an almost equally significant difference. Last was adding an X-pipe; though not as significant of a change, noticeable for sure, particularly when it comes to the 2500 rpm drone which is now gone. With those 3 changes the car is easily half as loud as it was and lost nothing at the track.

[70ptta]

So I found out what mufflers I have. They are Thrush welded mufflers part #17657 its a 3" exhaust from headers to the muffler and out the side so its a really short system. The muffler shell is 4"x9.5" by 13" long. Just want to see if you guys have any more opinions now that I know what muffler I have and a video even though its not a good one. thanks http://www.youtube.com/watch?v=2JwLxlNJaqk

[impalatpi66]

switch to a magnaflow

[flynbrian]

Full length collector headers? To keep the same tone and not have to cut up the exhaust system but quiet it down, They make a insert that goes into your collector at the 3 bolt flange. Its basically a plate with a slightly smaller tube through it and the tube is perforated with holes. They work well as a pre muffler and will slip right in with little work no cutting or welding. Jegs and summit both carry them.
It might even give you a tiny bit more torque if the pipes are slightly too big for the motor.

I build exhaust systems all the time...I prefer 3" but I do tricks to keep it right for the motor involved.
X-pipes give a great sound yet they do quiet a system alot.
My 69' Firebird used to be heard from 2-3 city blocks away thumping its way up the road with 2 chambers and turn downs...

Now with the X-pipe I can pretty well sneak right up on ya from behind...But you can still hear it pretty good after I go past.