Good tone, less drone?

So I'm trying to keep my 1996 5.7 Tahoe a pleasant place to haul family as well as racecar. It's a very high mileage but extremely well kept and rust free hauler.

Main gripe right now is the amazingly intrusive exhaust drone at highway speeds. I've done it to myself, as in the process of "repairing" I've installed a catless 2.5" Y-pipe that empties into a Dynomax 3" single exhaust system that exits through a stainless slash cut tip behind the passenger rear wheel. The drone is extremely throttle position and load sensitive, and worst from 2000-2400, right at highway 60-80mph cruising speeds

What's my best "bang for the buck" to maintain the breathing improvements but cut out the drone? Replace the muffler (single 3" in/out oval)? Plunk down for a pair of mini cats? Install a resonated tip? Leave the exhaust and invest in Dynomat/Lizardskin for the cargo area?

I'm assuming your muffler is a glasspack-type...Dynomax glasspack mufflers are lightly packed which makes them lightweight and cheap, but they don't reduce sound much as a result. Magnaflow uses denser packing (and a layer of SS packing around the tube to reduce packing blowout) so they reduce sound more but they're heavier and more expensive.

Is that 3" at the rear the only muffler in the system? If so your best bet might be adding another muffler further up in the system, like behind the Y-pipe merge. Add one with very different dimensions to the one in the rear - usually a long one helps reduce low-RPM drone.

http://www.speedwaymotors.com/Speedway-Shorty-Race-Mufflers-8-x-3-Inch,32791.html

This maybe? Read the reviews. For $10 it's hard to go wrong.

^I'd like to learn more about that model, it could be useful to me...if they made a 2.5" version that is. It says it has no "filters" (I assume they mean packing) so how does it work?

It's just a perforated core with an outer shell, like a completely used up glasspack with no packing left- they don't muffle a whole lot, but a few in series can do an OK job.

3" is the smallest I've seen, but if you find a similarly cheap option for 2.5" please let me know!

Tailpipe.

The single big oval muffler is fairly far forward, right behind the y-merge, more or less in the stock location (though stock is a dual-in/single out configuration). Then it's 3" back, over the rear axle, and out.

Edit: this is exactly what's installed actually... Exhaust from Summit

Regardless of their size, shape, or amount of packing, absorptive type "glasspack' mufflers don't attenuate the frequency range 80-150Hz that we percieve as drone very well:

You basically need a reactive type "turbo" muffler (or better yet, a combination of both) if you want to eliminate drone.

--Edit-- and now that you've mentioned already having a reactive type muffler, i'm guessing it's a case of "not enough". Adding a glasspack/bullet absorptive muffler would probably help catch the frequencies that the reactive muffler is missing.

I think the best bang for your buck and easiest to install is a resonator. My track car was not only loud but had a terrible tone to it. Dropped in a $100 Hushmaster resonator and 100% improvement in drone and sound quality. If you can find a slip fit it is DIY friendly to install inline before the muffler.

Any parts store has a variety of different glasspacks for about $20, many are directional so there's a loud way or flip it and it's quiter (instead of a perforated pipe it's got louvers/scoops). That's going to cut out all your drone for super cheap and no worries about shippin or waiting

Add a turbo, that always makes it quieter.

I like the idea of a pair of small cats and a resonator tip myself.

Perforated type glasspack (e.g Thrush), longest you can fit, before the muffler might do it. Or you can try building a drone cancel resonator.

chiodos wrote: Any parts store has a variety of different glasspacks for about $20, many are directional so there's a loud way or flip it and it's quiter (instead of a perforated pipe it's got louvers/scoops). That's going to cut out all your drone for super cheap and no worries about shippin or waiting

Yep, I've only driven on my custom exhaust for about 10 minutes but no drone was noticeable, and it has a louvered glasspack in the "quieter" configuration just behind where a cat would be, and then a Dynomax glasspack in the back.

OK, why the hell didn't I think of that? I'll borrow a frequency analyzer from work, find out exactly what I'm hearing :)

Kenny_McCormic wrote: Or you can try building a drone cancel resonator.

I'll check out convenient spots to drop in a new slip fit part... Walker and Jones both make nice short resonators that I might be able to fit. Not much free straight length in the system to fit a long tube style glasspack.

The Hoff wrote: I think the best bang for your buck and easiest to install is a resonator.