blackmamba-z

Hey everybody , was on the road this past weekend , coming from York pa to New York City on my way back I was cruising at about 75-80mph there was a point in time where traffic speed up so I did the same , a few miles later. I notice my exhaust sounded different , and I had a drone type sound and vibration coming from the front of the car , car still accelerates but up around 70 mph it would make that drone vibration , still cannot figure what's causing this sound I pull over rev the car freely and nothing , regular driving nothing only does it when I'm up around the 60+ mark anybody has a clue what's going on here

Injuneer

Info required - year of vehicle, trans type, any major mods to engine or drivetrain?

blackmamba-z

99 z ls6 engine swap , long tubes headers ,borla cat back , rebuilt transmission , Koni shocks, bmr springs ,adj pan hard bar ,bmr stb,lower control arms , just installed brand new rack n pinion in sept , the vibration start happening with a change in exhaust tone suddenly on the interstate , so I turned down my music n that's wat confirmed these symptoms

akwa

I would say to climb under the car and start pulling on stuff. See if an exhaust bracket might of came loose. Check that pesky air dam under the front bumper. Those love to come loose or tear and would make a humming noise but I'm not sure how it would play into the exhaust note unless you are hearing it wrong. Another idea that I have done in less populated areas is take a buddy with you and have him open the passenger door and hang out listening for the noise to help pin point it. I did that when my rear axel was making noise but from inside the car it just echoed.

blackmamba-z

I think i have a real bad exhaust leak, cause my gas milage is down as well and throttle response is slightly decreased

Injuneer

Do you still have cats? Possible one is starting to plug up????

blackmamba-z

No cats off road y , cause has different exhuast note now

blackmamba-z

Ok took my car to shop yesterday, n me n my mechanic was completely stumped , we check for exhaust leaks none, the car exhaust n everything sound fine from the outside but when in the cabin there is a slight grinding sound, and the exhaust sound completely different ,inside it went from the startard growl of longtubes and borla exhaust to a almost low flooded drone sound , acceleration still good no smoke no nothin im completely stumped atm