Exhaust sound question

[RufCTR]

I have a 2008 GT with Borla S-type rear mufflers (stock exhaust otherwise) and just installed an x-pipe yesterday. Interesting side-effect is that the car is now quieter..... has this happened to anyone else??

 

[Dubstep Shep]

Not sure this qualifies as tech... I'm sure a mod will chime in.

Any details on the x-pipe? Factory exhaust manifolds?

 

[mavisky]

X pipes are a bit quieter and will pop and crackle on decel more than a standard H-pipe, but also flow better and make more hp typically.

 

[BEAST]

Tekkkkkkk

 

[irishpwr46]

ttotd

 

[Blxcklist]

X is quieter than H design.

 

[RufCTR]

Not sure this qualifies as tech... I'm sure a mod will chime in.

Any details on the x-pipe? Factory exhaust manifolds?

The exhaust manifolds are stock and the x-pipe is a Pypes cut/clamp design I got used for next to nothing (inexpensive upgrade in my opinion).

I'm quite happy with the sound (for now) but was surprised to have the exhaust be quieter. Eventually I plan to gut the cats and tune the car, but I'm not there yet. I know it'll get louder at that point, but I'm okay with that.

 

[Dubstep Shep]

The exhaust manifolds are stock and the x-pipe is a Pypes cut/clamp design I got used for next to nothing (inexpensive upgrade in my opinion).

I'm quite happy with the sound (for now) but was surprised to have the exhaust be quieter. Eventually I plan to gut the cats and tune the car, but I'm not there yet. I know it'll get louder at that point, but I'm okay with that.

Gutting the cats is inferior to straight pipe. It basically turns into an expansion chamber and that's no bueno.

 

[RufCTR]

Gutting the cats is inferior to straight pipe. It basically turns into an expansion chamber and that's no bueno.

Very true, but that is why I am going to sleeve the cats and fill the area around the center pipe with muffler material. This will give the appearance of stock cats while still not having them. Here in California, the visual portion of this is critical... otherwise I'd just go with a straight x-pipe from the manifolds back.

 

[Dubstep Shep]

Very true, but that is why I am going to sleeve the cats and fill the area around the center pipe with muffler material. This will give the appearance of stock cats while still not having them. Here in California, the visual portion of this is critical... otherwise I'd just go with a straight x-pipe from the manifolds back.

Yea, that's the way to go. Combine that with a good tuner and you'll pass visual and OBDII inspections.

But doesn't Cali do exhaust gas testing? You can't pass that without an actual cat.

Your other option is 50 state legal high flow cats, which are still a huge improvement over stock.

 

[eighty6gt]

Aftermarket cats are garbage. I'd just leave it alone unless it was a big power blower car - this isn't 1996.

 

[Dubstep Shep]

Aftermarket cats are garbage. I'd just leave it alone unless it was a big power blower car - this isn't 1996.

Uhhh... the last time I looked at a stock cat vs a high flow there was quite an impressive difference...

 

[eighty6gt]

Doesn't mean they aren't garbage.

 

[Dubstep Shep]

Doesn't mean they aren't garbage.

So what exactly do you mean by garbage? Quality? Performance?

 

[eighty6gt]

Quality, obviously. Usually they'll have less restriction to flow than an OEM cat, but what we have available all cost too little money to be any good. I think Vibrant has real cats for sale, they are around $850/ea. Cheap cats just come apart/fail/don't do very much.

 

[claudermilk]

But doesn't Cali do exhaust gas testing? You can't pass that without an actual cat.

Yep. It became humorous/irritating when the old Probe was due for testing. First thing they would do is hook up the sniffer & run that test. Yay, the car once again passes measured emissions with flying colors. That's 10 minutes. The next 30 is to visually inspect that all the gear is there...which we just proved is all working correctly and the car is running clean. Sigh.