In an attempt to eliminate the stinky sound coming from my car, I slapped my 2nd cat back on in place of my test pipe. Sure enough, my car stopped farting up a storm and it's hella loud compared to before header installation.

However, there's a LOT of noise coming from my 2nd cat - to the tone of rumbling. I'm thinking it's the extra exhaust gasses making all the noise. Seriously, it sounds like my exhaust is sitting where the cat is sitting. I don't think it's a loose or busted gasket cuz I already know what that sounds like from just yesterday. That, and it was hell getting the cat back on cuz it's a tight squeeze with that downpipe being there.

Any suggestions or insight will be much appreciated.

 

what muffler do you have on? Are you referring to a "gurgling" sound coming from the exhaust or is it something else?

When I replaced my header there were some new sounds but I think it is just that you can hear more of the engine.

WADAD

 

no jon its the diff in pipe size unless u got all new piping mine did it before the cat back its cuse u go from 2 1/2 to 1 7/8 to 2 1/4 2 1 7/8 to if i remember right 2 1/2 its the diff sizes of pipe meaning its "catching on the smaller piping unblock me if u want a fix

 

Wadad - I've got an RMR muffler, and I heard that gurgling sound you're talking about also. That's one of the reasons I put my cat back on. Now, the only noise is coming from the 2nd cat.

Ryan - Good point about the size differences. As it is right now, I've got a 3" downpipe dumping into my 2nd cat. I'm gonna be picking up a highflow cat from RPW and hopefully that'll solve the problem.

 

also get a diff res i have the greddy cat back now and that got rid of 90% of my high pitched ness with my straight pipe exaust also get that catback complete the stock cat back piping is small and sucks i almost if hadnt goten the greddy woulda goten it at a local shop for $100 installed mand bent but like rob said when u get rid of the cats your runing from the block basiclly so its gonna twang a bit

 

Wow, that last post was amazingly OT. Can we please not clutter the thread with randomness?

 

I just got back from driving my car again and the noise is definitely coming from the end that bolts to the rest of the exhaust. I'm thinking wider piping (2.5") in the form of a catback section will clear things up.

 

I'll try to take a stab at this.

I know what you mean ghost. It sounds like the muffler noise is now under the car. This is what it seemed like to me at first but gradually I got used to it. I think it is because the exhaust is now louder that it seems like the sound is coming from closer to the driver. It's just getting used to the sound in my opinion.

I still have my second cat and when the car was dyno'd I had a chance to stand outside and really listen to the car being revved for the first time. It sounds great under revs.

It sounds completely different from behind the car but when inside the car you think you can hear like a "gurgling" as I called it with mild backfiring or so during smooth shifting. ( normal driving)

This has become less noticeable to me as time goes on.

I'm getting my 30K service on Friday so I am going to be interested to see if anything changes. This is my first real service since the header install.

I hope this helps a bit. I don't think there is anything to worry about unless your gasket has come lose again. Give it time

WADAD

 

Thanks a lot for the input wadad! I'm just not liking the exhaust sound coming from the center of the car. I'm picky like that, and I want it coming from my muffler dammit!

I think I am gonna go the custom catback route now and I'm thinking that'll clear things up.

 

Ok everyone, I need last opinions before I decide to embark on my project here.

My first option is to get a highflow cat to replace my 2nd cat. I'm sure that'll help ease the flow, and I'm wondering if that will alleviate some of the noise that I'm currently experiencing. What I'm worried about, however, is that it'll only INCREASE the noise due to the increased exhaust flow.

Which leads me to my second option of getting 2.5" catback piping done. With this, I'm hoping to get rid of the bottleneck where the 2nd cat and the stock exhaust piping meet, which is where the noise seems to be coming from. My concern with this, however, is that I'll go right back to the farting problem I had with my test pipe on cuz of the free flow.



So what should I do then? Either way, I'm gonna be doing something rather permanent, cuz I'll be selling my test pipe to get the highflow cat, and I'll be selling my RMR exhaust to get the custom catback.