I would like to upgrade to a 4" exhaust and would like to know if there are any systems that will give me both performance and peace and quiet. I'm willing to give up a little silence as long as I'm getting performance in return but if I had my way I'd be pushing 1000ft/lbs torque at 0-dba.
Yea I know, "It's not possible" but you catch my drift.

 

Give Rip Rook a call. He has years of experience with many muffler/resonator combiations and can probably put together what you need, or just give you good advice.

http://www.sourceautomotive.biz

 

Recently had the same question. Got advice to check RPM Outlet and wasn't sorry. Good price and the system is not loud. It does sound louder than stock but it's fine.

 

I purchased mine through Jardine and the resonance was just way too loud so they sent me another magnaflow muffler. I now have two straight through mufflers 4" and the exhaust is as quite as stock. Lets just say that you can't hear the exhaust over the engine

I did not notice any decrease in EGT's by adding the second muffler.

 

Did you notice a reduction in EGT after switching from the stock to a 4" exhaust?
How much reduction?

 

I really did know my EGT's, because when I installed the exhaust system I also installed the gauges at the same time. That is how I know it did not change when I added the second muffler. You know how much you stare at those gauges when new

 

I added a Magnaflow XL 4" system, and I thought that it was too loud. I then added to it a Nelson 51" muffler to the system (now there are 2 mufflers) and the sound was MUCH better. Quieter than stock, and my EGT's are running about 100-125 degrees cooler than with the stock system. The addition of the second muffler didnt' cost any increase in EGT's over the 4" system with just one muffler.

DeWain

 

I did some homework . . . . . . .

With the above, we're moving right at 1332 CFM through the exhaust system at 3000rpm.

In a perfect world, we'd be able to move all that through the plumbing with no restriction. The closest to that is the straight-pipe system.

As far as noise control goes, (note, I have no first hand experience with any of the brand-name systems), straight-through/glass-pack type mufflers (resonators) attenuate high frequency noise. They let the low rumble through. The baffled type mufflers attenuate the low frequency noise. While they do mute the high frequencies some, they also tend to contribute some with the baffles (it's weird science, do a Google). That's why you see both devices on the really quiet vehicles.


OK.



I've found that (outside of the brand-name packaged deals), many kits offer something like this; Muffler 4" In/Out 8.5" Diameter X 34" Body Length (Link). Here are the manufacturer's specs (Link)
Note: The rated flow shown, Low, Medium, and High, is at a given back-pressure (resistance to flow). That back-pressure is presented in Inches of Mercury (In Hg). 1 In HG = 0.4911541 psi, or just shy of 1/2 pound pressure.


In the Donaldson product line, that muffler is one of the highest flowing in a four inch pipe system. But it's also one of the loudest at only 8 to 12 db attenuation.



OK



Using the Attribute Search (Link) feature of the Donaldson website, I found one muffler to be the quietest while still maintaining a high flow with the least back-pressure.

This one: M110189 (Link). I call it the BHM (Big Honk'in Muffler)

The specs are:
As you can see, it flows the required volume with under 1 pound pack-pressure. AND, it attenuates the low frequency noise 19 to 25 db. A BIG drop in noise.

Now, it IS a Big Honk'in Muffler!

With a gross length of 45.5", and a diameter of just under 12", it's gonna be a close fit under my 1st gen (250 CC long-bed / Your mileage may vary). It's also a Round, Style 2 muffler, meaning it's inlet and outlet are not centered. With that, you'll most likely have to move your pipes a bit to get them to plug in.



I expect it to hush things right up. I'll let you know (it's sitting in the living room as I'm waiting for the manifold and turbo to show up).


Hope this suggestion helps.

 

Wow!!!
You do good work.
I may have missed it but are you going to be running a resonator as well as the BHM.
It has been suggested to do both by a couple of different people.

 

For the moment no, I'm not gonna run the resonator. It may be quiet enough. If not, I'm planning on slipping in This One (Link). Specs (Link).



The one supplier I'm linking to is only for images of the muffler/resonator. Donaldson is the mfg and can often be purchased competitively locally. (That's fancy talk for shop around). Another major manufacturer is Nelson (Fleetguard) (Link) They have a cross for it if need be. I guess it performs the same. Their website specs aren't as descript as Donaldson's.