I have a stock exhaust, and all of a sudden, one day I start the car and start driving, I realize my exhaust is kind of louder than before...
it's been raining for a while, maybe that was the problem?
what coule be the problem? muffler?

 

prolly a hole in your muffler or mid-pipe. Happened to me a few times, what year do you got?

 

yep prob. a hole time for a cat back...

 

I have a feeling your muffler may have a hole in it. If your exhaust piping has a hole it in, get that fixed asap, nothing like having and exhaust pipe crackin half on you while you're on the highway.

I had a hole right where the resonator and pipe meet, and I gave her alittle gas and all of sudden my car made the loudest sound. It's pretty much like running open header.

 

I had my exhaust crack in half on me on the highway on ym old civic. It sounded like a jet about take off, loud as hell.

 

Yeah man, that ish was ridiculously loud. The only thing louder was when my friend and I ran his El Camino open header.

 

or the rings and stuffin the catcame off cuz thats wut happened to me on my old si and it sounded sooo loud

 

wow.. and El Camino run open-header... can you say "hearing loss"? lol

I'd say just get a cat-back and not worry about why your exhaust is loud (btw my guess is ahole in your muffler)

 

That just happened to me 3 weeks ago. I already had new headers and recently replaced my cat. I got to go guy shopping and found a nice Tsudo catback exhaust. It fit like a glove. Gotta love eBay.

 

My car got loud one day. Was driving down the AC Expressway and heard a grinding sound. My exhaust pipe had rusted right before the expansion chamber and fallen off. So you probably want to get that checked.