lgndryhr

I installed Stainless Power 1 7/8 with off road pipes on 9/5/15 with approximately 45k miles. Tuned trans 9/24 then did datalog and MAF adjustment on 10/10. Don't have a wideband yet.

This is two videos of a strange noise I hear once hit anywhere between 60-80 mph. After that can easily hear sound at any speed under load in any gear. Cannot replicate when parked. Noise doesn't appear if car stays cruising around town. Checked last night all of my clamps and nuts. Checked under hood. Cannot find anything. Wondering if it's my lifters.

Video 1 is when I first hit 60-80 mph and the sound starts.


Video 2 is after I ramp off highway and drive around 45-50 mph on street.

tadams72

Just a guess but check that aluminum heat shield in the tunnel. Wondering if at speed turbulence is rattling it against the body or exhaust.

lgndryhr

I will definitely check that tonight. I checked the tunnel brace last night and it looked okay.

lgndryhr

Removed tunnel brace and checked heat shields with help of a friend. Still made noise. Checked motor mounts and they were okay. Yesterday, finally found area of sound. Heat shield and resonator area. If I hit the resonator I can hear the sound. Can replicate in park now too. Sound has changed and sounds like vibration moved further back.

Ordering an aftermarket catback to get rid of the ugly L99 resonator and trash can mufflers.

01WS6/tamu

iTrader: (37)

Sounds like exhaust gas flow through the headers under throttle pretty normal sound. Adding headers adds NVH to a vehicle it's probably just a new noise to get used to. Kinda hard to diagnose over a internet video. Check to see if headers are hitting body structure or braces under throttle look for rub points as transmitted noise can be highly exaggerated.

FourG63 97GST

iTrader: (1)

get under there with a rubber mallet, hit all the things till it shows it's face

rdame

I just installed a catback on my 2011 ss. When I held it up with a jack the heat shield got bent and was just kissing the drive shaft. I noticed the marks on the shaft. Barely touching but sounded horrible. I bet it is a heat shield. Had the same kind of sound.

lgndryhr

It ended up being the stock L99 resonator. The welds inside were broke or breaking. Replaced entire catback with Stainless Works Retro Chambered with correct pipping for a true 3" connection to my long tubes.