Problems?, with new muffler

[cpsd40]

Hello all, I'm new to your world of Vibe topics so bear with me. I'm posting this for a friend who is without computer access right now. He just finished installing a new muffler and exhaust tip to his 2003 Vibe. It's the base model with a 5 speed. It seems now when he downshifts it, as the rpms come down, he says it pops or snaps or something like that, out the exhaust. I'm sorry I don't know what kind of muffler it is, but the tip has two outlets close together, angled upwards at a 45 degree angle. He is wondering if it should be doing this and if it may be the tip or muffler or a combination of both causing it. He says he can live with it if it's something it's supposed to do. My wife and I have a bone stock 2003 Vibe AWD, it makes so such sounds at all. Thank you all for any help with this, cp

[noginsk]

Do you recall if your friend's vibe was making any noises before the muffler install? Was the exhaust a full catback or just the muffler? Has your freind done this kind of thing before, you know installing exhausts? This sounds s little too weird to be normal. I drive a stock base 5speed too, but no exhaust. No sounds like that here.

[ViciousRR]

I would assume it is a performance type of muffler. If it's just the muffler, it's not all that uncommon to see or hear a back fire when letting off the throttle. Usually a cat-back or full exhaust helps fix that.

[cpsd40]

It sounded just like any other Vibe before he did the modification. I went and took a closer look at his setup. It seems it's just the muffler he changed. The pipe ahead of it looks undisturbed. This was his first time doing this and he did it alone, but I checked things out for him today. I'm a railroad diesel mechanic and small cars are a little out of my field, but I couldn't see anything wrong, no leaks or something hanging out of place. I agree it does sound strange and out of place. I haven't heard any other Vibe, including my own, do anything like that. Thanks for the reply, cp

[cpsd40]

He said he bought it at a speed shop?, so i'm guessing it is a higher perfomance muffler. In looking at it today, it's short and oblong and is quite a bit louder than stock. I'll let him know about your suggestions. Thanks for the help, cp

[MadBill]

Even a very slight exhaust leak can suck in air on decelleration, mixing with and burning small amounts of unburned fuel and causing combustion "pops". (The stock system is 100% leak-free, plus is so heavily baffled that you likely wouldn't hear it anyway.) I have a cut out pipe on the right side of my Vibe, connected upstream of the muffler with a sort of throttle blade which when closed sends all the exhaust through the standard muffler. With the valve open I get an occasional pop just as I let off the gas, but with it closed, never.I'd momentarily block the exhaust outlet with the engine idling and have someone listen very carefully for any hissing at joints, etc., then re-weld, add muffler cement, etc. if necessary to eliminate the leaks. That should get rid of at least 90% of the problem, but the last 10% may require changing driving habits a bit, e.g. lifing off the gas less abruptly.