Help please: Weird exhaust burp sound around 5,000 RPM

I went for a drive today and started getting this constant loud burping sound on my mufflers on 2nd gear at around 5,000 RPM.
Car runs fine. Exhaust sound is normal below 5,000 RPM and higher than 7,000 RPM

Anyone else experienced the same issue?
What was the culprit and what did you do to fix the issue?

My car is a 2003 360 F1 Spider with 21,000 miles. I have a non valved Tubi exhaust installed.
Car ran perfectly and exhaust sound was normal before today.

Any help would be greatly appreciated.

Thanks in advance.

Dan

 

Yes the burping sound starts at ~ 5,000 RPM and if I hold it steady at 5,000 RPM the burp sound continues. Once I accelerate to about 7,000 RPM the burping sound goes away. Really weird.

The burping sound is like an exhaust valve being opened but I have no valves in my Tubi exhaust.

I will try and record the sound this weekend and post it here.

Thanks for chiming in.

Dan

 

Yes the burping sound starts at ~ 5,000 RPM and if I hold it steady at 5,000 RPM the burp sound continues. Once I accelerate to about 7,000 RPM the burping sound goes away. Really weird.

The burping sound once it starts is like an exhaust valve being wide opened but I have no valves on my Tubi exhaust.

I will try and record the sound this weekend and post it here.

Thanks for chiming in.

Dan

 

I want to provide an update to this thread of mine.

The fault code thrown was accurate. Pre-Cat sensor was bad.

Removed and replaced both pre cat sensors and this issue went away.

Dan