Never ending quest for the best C4 ZR-1 exhaust system- Stainless Works

[XfireZ51]

Originally Posted by emmvette

That looks like a great set up. Thanks for sharing!

What is the reason for the drone? I've got the drone in 6th at 65-75, which is unfortunately normal cruising speeds. Is it just a resonant frequency?

Is there anything that can change this on an existing set-up? I've got a nice exhaust with headers, so no reason to spend more $ on mine.

Here in FBIland, we 've been using the Z06 exhaust control valve. It seems GM decided it was cheaper and weighed less than a resonator to control drone at cruising speeds (on mine that's anywhere from 1400-1800 rpm). I think there are several factors that can help mitigate drone:

1. A too flabby (rich) tune will give the exhaust more of a blub blub blub sound particularly on an incline when the MAP goes higher and RPMs drop.
I like a bit of a leaner AFR for cruise. Found it tightens up the exhaust sound bringing it into a higher frequency.

2. I think the double walled construction of tips like the Z06, Corsa, MagnaFlow also help. The exhaust opening of these tips is shaped more like a trumpet while the outer portion of the tip is cylindrical. IMO, this cuts down any resonating the tip would generate. The B+B for example are single wall. AL has driven my car and BobGs car, different CIDs but both using the Z06 tips. Meanwhile Pete and Al use the B+B tip w the control valve.
AL has noticed that even tho each car uses the control valve, Bob's and mine seem quieter and less resonance.

3. I think the tips should extend at least just a bit past the rear valence panel. This avoids dumping the exhaust towards the rear panel and setting up a resonance.

The above are strictly based on observations involving my car and some of the other FBI ZRs. Your results may vary. Also, I have used:
1. stock exhaust
2. B+B 3rd Gen
3. Magnaflow C4 catback both w and w/o resonator
4. SW Xpipe w Magnaflow mufflers and tips/no resonator
5. Current system is Watson headers, 3" SS pipe, SW Xpipe, DynoMax
Ultraflow muffs w Z06 tips and exhaust control valves. I have posted vids of the exhaust previously.