I have a Dansk 2in2out w/ssi on my 3.0 in my 72, I had drone but the idle noise was crazy too. I capped one end with a reducer (2.2-2) from Krager slid right in and just welded the cap on first. I also tried putting the reducers in both sides without the cap so I actually had 2" tips now and not only was that quiter if seemed to have better response, remember a dual tip anything bigger than 2" is overkill for flow.

I rigged up a spring and flap as well in the reducer but have not tried that yet as I am buried in front end stuff and fuel pump repair. I can take a pic if you would like.

M&K 3" dual outlet here. No drone. Can't explain it. It is loud though.
I added the car chemistry exhaust inserts to both outlets. This reduced some of the noise, but not significantly. It made no discernable difference to power.

Wavey,
Please let me know if the cap affects power on your dyno run. I've been thinking about putting an internal cap in one of mine to reduce noise, but didn't want to reduce power. I like how the dual outlet exhaust looks.

http://forums.pelicanparts.com/uploa...1269020187.jpg

I have the same 911R muffler from Ben, but with 2.5" tips and running 1-5/8 European Racing headers, and have a drone from 2600-3500.

Drone is usually from sound waves colliding. So things like primary pipe diameter and length, overall length of the exhaust from the heads to the tips, diameter and length of the tips etc. Many years ago (like 20) I'd made a 2-in, 2-out muffler from a stock 2-in by cutting the top off, modifying the internal baffles, and added a second tip on the right to match the stock tip on the left. All based on drawings from the good folks at SSI. When I ran that muffler behind my 1-5/8 Bursch headers, no drone. But swappping to the SSI's for winter, I had a nasty drone. Only difference was the diameter and length of the primary pipes.

I think back to the 70's and trying to figure out where to put the crossover on a Z28 with headers and dual exhaust. An old drag racer told me to paint about a 3 foot length of the exhaust pipe behind the collectors with gray primer and drive the car hard to get the exhaust really hot. Then look for the white spot on the pipes, that's where the sound waves were hitting the side of the pipe, and just where the crossover wants to be. Worked every time and smoothed out the sound as well. But that was also when we had to gap points and set distributor timing too. And ran on Firestone Wide Oval bias ply tires too.

Here you go -

No baffles:
http://forums.pelicanparts.com/uploa...1269028181.jpg

Reducers in both sides, still droned:
http://forums.pelicanparts.com/uploa...1269028225.jpg

Blockoff in one side, no drone:
http://forums.pelicanparts.com/uploa...1269028267.jpg

These bolt in through the bottom, about 5" back from the tip. I'll try to get a dyno run with it open and with the blockoff, but I only get 2 runs, one right after the other. They're free runs and they may not allow the time. I'd like to compare my Wong and Russell chips too, so I may go back and pay for it.

Where did you source the reducers?

Thanks Wavey.
Bob, I believe Wavey made them.

correct.

Could the droning have something to do with all that extra exhaust plumbing some of you guys have under there? SSI's to muffler is what is on my car and it looks like the same goes for DW's car (kinda sounds like a NASCAR commentary!) which appears to be a 3.6.

Also, worth pointing out (has been sorta mentioned) that RSR type exits are (or should be) a different animal than dual outs that are closer to center.

Point is it might not be correct to say 'all 2 outs drone'. Might need to add 'on 3.0 and 3.2 cars that don't run SSI's straight to the muffler'. Not positive but it seems possible.

My RSR style 2-2 has the pipes about 8" apart. Drone is amazingly loud.

Funny how it is very loud inside the car, and not so bad out side. My wife drove it around the block and it seemed no worse than a warmed over Harley. Inside! More like a straight piped Harley pointed at the back of your head.

Close the windows it's not too bad. Open windows, engine warmed up. Ouch. With that 2-2 on, I just keep the tranny in a lower gear, to keep it above 3000 rpm. But mostly, that 2-2 sits in my basement. Too loud for LRP. Too loud for day in day out driving. Too bad, it sounds great at 4,000-6000 rpm, and idle to 2000 rpm.

We may be faced with a car shape/volume combination that makes the 2-2 even worse.

This is the setup that I want with my 3.6. What version of Ben's muffler is it? When you say loud, it that outside the car, inside the car, or both?

Pretty sure that is the 'R' style muffler, and they are loud. Ben can make the outlets smaller, which he did on my car (2") and it's still is pretty loud. I don't have this muffler, I have the one that wavey has.

I said "almost" all 2-outs drone, and I stand by that. But whatever:D

Ah ha. Thanks. Nice work.

Wavey, I don't suppose you want to start a cottage industry?:D

If so, I'm on board for a 2 1/2" to 2" or even 1 1/2" reducer.

I have found from all my testing is that our 2in2 outs drone @ 2400 and completly disappear @2850 now it depends on gen muffler and engine config/cr ratios ,gearing,etc

That RPM-range for drone is exactly what I found with the MK and the Dansk 2in/2out on SSI's.

Ben's 2in/2out muffler is well-made, it gives a noticeable increase in performance and I highly recommend it for track-use.

Not sure if a 1in/2out would have similar issues? Probably not.

Thanks, but I'll pass :)

Mine's a 1-in / 2-out and has the same issue.

I should mention that after some miles, with some carbon build-up, the drone seems to lessen (I've read others comment about this too). Mine has about 17K on it and has quite a bit of build-up, due to running very rich at least some of that time. I pulled the one-side baffle last week to do a dyno run, and the droning is definitely less than when it was new.

Reducing the size of the outlet pipes from the muffler definitely helps. There was a thread 5 - 6 years ago by Jack Olsen that came to this conclusion about solving the 2k - 3k drone. Make your exhaust tips 2 - 2.25" and your problems will disappear.

Mine are 2 inch and it still drones, and at certain rpms it will set some car alarms off. I read that someone wrapped their muffler with high heat header tape and it helped alot, but what a hassle that would be.

Not to mention a water trap promoting rust............