I'm on my 3rd cat back exhaust system.

I now have the Buschur Racing Magnaflow system. I got it for the power, but it's much more quiet. It also gives me the option to easily swap or remove the muffler for racing.

I also take my family in it and I don't worry about my young son's hearing anymore.

 

Just another datapoint... I built a custom exhaust with top priority being *NO* drone. It turned out exactly like I wanted. The thing sounds like an electric car until you step on it, then it sounds "nice" but not ridiculous. And this is even with no cat. Anyway, here is what I used:

Helix 3" downpipe, I cut off the cat flange and added a v-band flange instead.

Greddy Evo2 catback, I cut off the front 2-3" where it necks down and instead welded a 3" Vibrant resonator on there. At the front of the resonator I put another v-band flange to mate with the downpipe. The greddy catback has it's own resonator near the muffler, so this system ends up with 2 resonators and a muffler. When I do the new turbo and stroker I may remove this rear resonator because, unlike the vibrant piece, the greddy resonator necks down on the inside putting the ID at less than 3". If I remove that I will likely replace it with a shorter vibrant resonator (12" vs the 18" I used up front) instead of a straight pipe. I hate drone!!

So I guess all of that is just a long-winded way of saying that if you start with a reasonably quiet catback and add a resonator, you can get a really quiet system even with no cat. (With a cat in addition to all of this you wouldn't even know the car was running!)

Hope that helps.

 

Man, that Greddy is 80mm piping, isn't it? And they neck it down under 3 inches at the resonator? Thats too bad! Please post again if you take that section out and comment on the difference. Significant custom work you've got into that exhaust. I thought I was picky!

Borla offred me a "venturi" - a pipe insert before the muffler that necks down a little and is supposed to change the sound. But they would not guarantee that it would be quieter, only that it would lose a little horsepower.

They also said that their exhaust was good for a 20 percent horsepower gain.

I didn't bother to argue that one...