Idle pauses. After catbypass pipe install. Air Bag Light??

[ProjectM96]

Hey. I just installed secondary bypass pipes with new gaskets and bolts yesterday.

When I rev to any rpm. Lets say 3000rpm. And I let go of the gas. It stays at 3000rpm for an additional second before goes back down to idle speed.

When revving passed 4000 rpm, I hear a whistling type of noise from the exhaust. Are they related?

Any idea what could be causing these?

Everything seems tight except where the bypass pipes meet the U pipe connecting it to the Muffler.

The bypass pipe is inserted into the U Pipe and it is a tight fit I cannot move with my hands, but the bolts for the clamps on the U pipe are not currently installed. So exhaust gases could potentially leak from there. That is my best guess for now.

Last thing, My air bag light randomly lit up for 3 seconds, then shut off, then back on, then off. This was about 1 hour after driving for the first time with bypass pipes. Don't know if it is related or what it could mean.

Thanks.