: exhaust modification - sound

09-05-12, 10:58 AM
This generic question applies to any model with a modified exhaust system. I happen to have a CTS V wagon with a manual transmission to which I installed Corsa mufflers because it was just too quiet. I love the new sound - rumbles at idle, quiet cruising and nasty when I push it. On deceleration it burbles and there is some "popping". It also "pops" when letting up on the throttle to up shift at above 2000 rpm in the lower gears. There is less of this if I shift more conservatively at lower rpm, power shift or only engine brake in the higher gears. Is this "pop", which I was told is common in high performance engines, a backfire, which I would think could be harmful, or a normal engine sound that is suppressed by stock mufflers? My question is essentially, must I avoid engine braking and strive to granny shift or can I drive normally and enjoy the music?

12-15-12, 02:00 PM
Wrong forum. Off to later CTS-V.

The engine/PCM will disable the injectors on long or forced coastdown operations. The pop you hear is a slight exhaust system "backfire" caused by the fuel cutoff - my STS does exactly the same thing when I (often) wring it out.