ps374

I have read a lot of posts about C4's having a drone sound at speeds around 50 MPH. There have been all kinds of advise given to eliminate this noise with after market exhaust systems. My question is does the STOCK C4 exhaust system also have the drone noise at 55MPH.?

Richard Raichert

My stock 94 has no drone at all.

Silver96ce

Not that I have ever noticed.

RollaMo-LT4

It isn't so much the speed as it is the engine load at certain RPM's.
In the 1800 to 2000 RPM range in the higher gears will cause the drone with most aftermarket exhaust systems.
The Corsa systems are said to have very little to no drone though.

And no, the stock exhaust system wouldn't have the drone.
Only the louder mufflers or muffler eliminators.

Tommycourt

My 88 convert. still has stock exhaust (I believe it's Walker) and I have no drone regardless of the speed you drive. My car is completely stock.
Tommy

bogus

verts don't drone...

FASTAZU

As long as the stock system is unmolested it will not drone..

playsdixie

headers. no cat/mufflers....can't hear the drone over the roar...

65Z01

My first '88 came stock with no drone, TPIS Flowmasters brought deep sound & drone, later Magnaflows brought alarm triggering sound with more drone.
This '88 has ?? exhaust with no drone and mild sound level.

sweeeeet...

playsdixie

if you can open this, you can hear'em

Klondike

The drone seems to be worse with cars that have eliminated the stock resonator.(The center muffler that BOTH exhaust pipes pass through that is right behind the cats but ahead of the rear mufflers) With the resonator removed and replaced with straight pipes with no H or X pipe, the length of the pipe to the mufflers in the back is just the correct length to set up a resonance at certain RPM's that will drum your eardrums to death. It's like blowing across the top of a bottle to make it whistle. Only on the exhaust, it's very low frequency like a low note on a super big pipe organ! I'm sure the GM sound engineers worked long hrs on the tuning and placement of that resonator.

murraybob

No drone. My stock exhaust is rather quiet at all speeds.

Tommycourt

I would add this though, I would like to have some Flow Masters or Magna Flow exhaust so I can hear a little roar go through the exhaust but I don't want to blow out the neighborhood or have a sound that will drive me wild on a long distance trip. A sound similar to a light glass pack would be nice to have. But for now, my exhaust is in good condition and I would rather put my money elsewhere, like tires, rather than have the sound resonance. We have to pick and choose our evils.
Tommy (sigh)

1993C4LT1

No drone, but factory exhaust note sucks!

C4.Ray

93' C4, 95% Stock = No Drone ( Thank God ). Only aftermarket exhaust proven not to drone is CORSA. Drone is a very serious noise problem, and many guys dismiss it as a minor issue, however these same guys when they reach 60+ years of age, all that drone will come back and bite them! Drone is a very real, and very serious problem to the human ear.

I advise leave your C4 exhaust stock or add the Corsa.

lt4obsesses

Agreed that the stock set up will not drone. Keep in mind that drone is caused by sound waves. These sound waves, at a certain pitch or frequency will cause stuff to vibrate. It's when these sound waves start to 'harmonize' that drone starts. The trick is to cancel those waves that start this harmony. This is what x-pipes, resonators and the like do.

When I first cut off my mufflers, I really hated the resonance (another word for drone) at 2 to 3K rpms. So I replaced the resonator with a muffler that had an internal x-pipe. This was an absolute cure. Another thing to watch for when modifing the exhaust, is the where the tips wind up. Best place is about a 1/4 inch past the bumper and at a slight downward angle.