ashmostro

iTrader: (3)

As the subject states, I am curious as to how the combination of completely stock CBE and headers, coupled with Berk (or similar) high flow cats would sound on a g37 sedan. Will it rasp? Drone? Or will it just sound a bit more aggressive?

Thanks!

Rochester

iTrader: (9)

Kind of an odd question, because headers will negate the cats.

G37Sam

Did you read OP's post?

He's only swapping out the cats, everything else will remain stock

I think it would sound nice, deeper & louder stock note basically

Rochester

iTrader: (9)

Did you read it? He said he wants High Flow Cats with headers and a stock cat-back.

Let's assume he doesn't know what headers are... there are lots of videos available. Youtube is fun.

Before & After BERK HFC's - YouTube

Redpit

iTrader: (2)

I think Sam is right. Judging by the op's title and his wording I would think its safe to say he is just talking about replacing the cats. To the OP it sounds pretty good. Just my $.02.

ashmostro

iTrader: (3)

Yep fellas, only item I am talking about replacing are the cats. Stock headers, stock CBE. Sorry for the confusion.

The reason I asked is, sound doesn't always do what you expect it to. I worry about resonance weirdness and potential resulting nasty sounds like rasp on overrun, and drone at specific RPMs on the freeway. These are both things I despise.

What I'm looking for is reduced backpressure, with slightly more aggressive tone and snarl, but not an "aftermarket" sound level. Also, I don't like how a lot of the aftermarket exhausts look conspicuous. Stock looks great to me. I like sleepers (that's just my style, I don't judge what others prefer).

Thanks for your opinions (keep em coming!) Also, thanks for the youtube link. I also saw some of those vids but the fact is, mics don't hear the same way humans do, and there's little frame of reference of sound level to make an assessment off of. I trust your opinions more than I trust the recordings.

Rochester

iTrader: (9)

No problem. True enough about videos. Even more so, revving the engine while in neutral, with a microphone at a fixed point, is entirely different than an engine under load. That particular video is pretty good, though, with a decent before/after comparison. And that "after" component is nice.

As for the confusion... tubular exhaust manifolds are headers.

Redpit

iTrader: (2)

My only experience with HFC's was not a good one. It did sound nice, but constant cel's was a pain. Especially in a state where you can't pass yearly inspections with a cel. This was all on an RX-8 though, but I'll never mess with HFC's again.

ashmostro

iTrader: (3)

I know... what about my posts implied that I didn't? I just looked to see if I wrote something to that effect but don't see that I did... ?

thanks

ashmostro

iTrader: (3)

Hmm, were you not running the O2 sensor, or was it running in the wrong location (ie after the cat)?

If this is going to happen with my car i wouldn't want to do it, but I though the CELs on our rides came more from test pipes than cats. Right?

Redpit

iTrader: (2)

Yeah the G may be different, but it just left such a bad taste in my mouth that I won't personally mess with it again. Regarding the O2 sensors, yeah it was all correct. It ran without a cel for a few months. It was not a cheap one either, I spent close to 1k on it.

The thing that sucked most is I researched it for a while before getting one. The consensus was it would not throw a code, but I was one of the few unlucky ones. I am in no way saying its going to happen to you, but figured I'd give you my experience with HFC's on one of my previous cars.

ashmostro

iTrader: (3)

Word. Thanks dude.

Rochester

iTrader: (9)

My last car, I had the pre-cats gutted, and wired an O2 Simulator into the secondary sensors. Worked very well. Anyone want to chime in on who makes an O2 Sim for the G37? Because IDK the answer to that.

The alternative on that particular car (2003 Maxima) was to extend the bungs for the secondaries, typically with a Spark Plug non-fouler. Somehow by extending the sensor slightly outside the exhaust flow, it was enough to trick the ECU into thinking the catalyst was being effective (when there was no actual catalyst). I'm fairly sure that's a common trick, but again... IDK how well that works on the G37.

However, either approach is only relevant for test pipes or headers (that word again, LOL). From what I've read here so far, the general consensus is that HFC's don't throw codes on the G37. I can't speak from experience on the HFC's just yet, but it certainly does seem the best drop-in bang-4-your-buck exhaust mod.

BLamb

iTrader: (1)

will the HFC pass the emissions tests if they don't throw a code? I thought they put some sort of measuring device at the tail pipes to determine if it was ok, or do they only check for codes?

Rochester

iTrader: (9)

According to this, Texas doesn't sniff. They just check for codes.

TxDPS - VI Emission Testing