I have a bad exhaust pop when deceleration and then touching off the gas again to accellerate. It first started when I got a muffler and then had a custom pipe made to go straight back to the cat. It only happens in gears 1,2 and 3. Its just this bad pop and it seems to get worse and happen more often. Is this something to be greatly alarmed about and is there anyway to help it? Any help would be great. Thanks

 

It's normal, every Impreza does that once you change the exhaust. It's a character trait

Some exhausts will pop a little bit quieter, but overall its harmless... well unless a pool of gas is pouring out your exhaust and you shoot flames

Korey

 

Yep mine pops as well.

 

The popping is unburned fuel lighting off in the cat, If I remember correctly. I like the sound myself, but it will shorten the life of your cat converter, since the fuel is exploding in it, and the lattice inside the cat is fairly thin to promote airflow and prevent clogging. Too much popping, or having it for a long time, will eventually break the converter, but that just means it's time for a good aftermarket high-flow cat I don't worry about it on my car, no reason for you to worry about it on yours, unless it just plain irritates you.

 

Or if the inside of the cat breaks down you could just leave it alone unless you live in a state with a vehicle emissions test.

 

I am now at 37k miles and had car just a tad over a year and the catalytic converter is shot and reeks bad. Well I guess it is the time to pull out the stock cat and go to a Random Tech cat to make it sound better and set off more car alarms. LOL