My mechanic's thoughts on the Berk CBE & HFC
 

So I just dropped my car off with my mechanic with whom I've given business for many years. Very professional, very honest guy.

Now, I'm trying to learn as much as I can about my car and at the same time could not hesitate on getting the exhaust done. I wanted some power gain and definitely a nice sound.

I dropped my car off with him along with the Berk Tech CBE exhaust and HF cats. He immediately started to shake his head and attempt to convince me that there won't be much flow over the stock cats. "You'll be back in less than 2 years with a CEL. So don't say I told you so." He even excluded the cats from the work order documentation and said "We'll just say these were already installed if anyone asks, these are likely illegal and you probably got scammed."

He also mentioned the platinum on a factory cat vs. a lower grade metal on aftermarket parts. He's obviously favorable to leaving a car stock.

We put the car up on the left, and he began mentioning that the car has 4 cats...? He was pointing at the piece between the cat and the header -- isn't that still part of the factory cat?

I'm still having him install it after my rebuttal of "Well, I read lots of great reviews about this setup on the community I visit and seen countless videos of the setup with praise."

Did I miss any steps in my research? Are these HFCs not worth it (or scam)?

It was very difficult to argue with a mechanic when I know little about cars in comparison, but I have been so excited about the install I didn't want to box them back up and ship them back.

When I pick my car back up in a few hours, is there anything I can tell him to have as an argument on why it was a good idea? (aside from the obvious fact aftermarket parts are a huge frown on anyone that prefers factory parts and isn't exactly into modifying a $30,000 car under warranty -- I just couldn't deal with how quiet my car is. But now I'm feeling like I'm adding a sweatshop re purposed piece of metal that belongs mickey mouse'd on a beater)

All thoughts and advice are greatly appreciated :tiphat:

I'll keep it short and sweet. There are guaranteed gains from switching out the stock cats, whether it be high flow cats or test pipes. There has been on-going research done time and time again ever since the G37 first came out with the VHR motor in '07. I'm not saying your mechanic is wrong, but I would take what he's saying with a grain of salt.

Actually it should be the other way around when you mention about the sweatshop exhaust. The stock exhaust is made of mild steel and has play-doh welds as you can see on the piping for yourself. At least with aftermarket exhaust systems they use anywhere from 409 - 304 stainless steel with better welds. You made a GREAT decision upgrading your exhaust and should be happy with the outcome. Not to mention, it's not a placebo in terms of power gains.

Lastly, if you end up getting a CEL just have your mechanic install some non-foulers and that will completely eliminate the problem.

- Steve

Time for a new mechanic ....

What are non-foulers?

There is nothing wrong with the purchases you made. Yeah, you may get a CEL but thats part of the game. Once you get intakes, if you do, you are gonna want to have the car tuned. Once its tuned you wont ever get a CEL again. You will see and feel definite gains from the CBE and HFC. DONT LET YOUR MECHANIC SCARE YOU, you will thoroughly enjoy your mods.

I would have left right then and there. Don't let him do anymore work on your car.

:iagree: 4 cats? Really? Tell your "mechanic" to :gtfo2:

:iagree: An exhaust upgrade has been dyno proven to have results, not to mention a better sound. Heck, even Nissan technically offers an aftermarket exhaust with the Nismo S-Tune. Most high flow cats are technically "off-road" use only, so your mechanic is technically right about the not being legal part. Most don't usually throw a CEL though, unlike some test pipes. You gain horsepower by removing the restriction created by the cats. Unfortunately, it also has the counter-effect of being less emission friendly. I have no idea what he means by 4 cats. Chances are, your car will be fine. An exhaust upgrade is one of the safest mods you could do. The worst thing that could happen is you mess up an 02 sensor, but its unlikely with HFC's.

They're extensions that you put on the 02 sensor that screws into your cat or test pipe. It basically fools the sensor into think you still have a restrictive cat on the car because it pulls the sensor farther from the exhaust gases.

Cool, I appreciate the responses. I feel much more comfortable about it now.

It sucks, because he's a really cool guy. He's done a lot of work to all my cars before with excellent results and with much better customer service than anyone else in this valley. I guess he just wasn't the best choice for this particular upgrade.

With that said, the muffler shops around here are even worse. I mean, the top name that floats around here put the wrong size muffler on my buddy's truck and welded the pipes all uneven, then gave him the run around for a week before fixing it. No way in hell was I gonna let those guys touch my car.

It sucks not having the tools necessary to do it myself or the connections to get it done. I end up stuck having to deal with all these shady mechanics out here, or in today's example, a mechanic I trust who's now going against my decision.

*sigh*

Thanks again

I take it your mechanic is some older guy? Maybe not up with current times?

HFCs will give you power as well as your cat back, so don't fret.

Most of the HFCs I've seen for the Z have "J" pipes installed for the O2 sensors. This pulls them away from the exhaust stream like another poster mentioned. This "should" avoid the CEL, if not you can try some extensions called anti foulers.

With the tuning, the reason you don't see CEL is because the O2 sensors are usually turned off. That's fine from a CEL perspective, but if you have to pass emissions that will show up as a "not ready" sensor and you might fail emissions. Just be aware of that and hope the "J" pipes do their job.

:iagree: ...4 hfc???

maybe 4 cats = 4 O2 sensors?

Maybe there were two actual cats living just south of the manifolds. Ya never know.

:icon18::bowrofl:

Yeah I'm not sure on his confusion about 4 cats. He pointed to the piping in front of the cats (not the exhaust direction, the other side. Between the cat and the headers I guess?). So, almost as if he made it seem as if there was an additional cat in front of each one. If that makes sense.

Not sure what would compel him to think that.

Not gonna lie, i lol'd haha

:icon18:

Everything between the headers and midpipe on these cars is a huge restriction on your exhaust. So anything that opens that up (HFC, LTH, or Y pipe) will see a large increase. The rest of the exhaust, get what you like :)

Come on meow, that's a little far fetched...

In for the lols


A lot of mechanics identify cats by looking for the heat shielding, if a factory exhaust has bracing or just heat shielding for the heck of it, they usually yell cat!!

Which helps us all out when it is time for an inspection

Just picked up the car. He said everything went smooth, and it does sound really good.

Only thing is I can *definitely* hear air coming from where the cats are. At high RPMs on the road it's noticeable, and when I have the car stationary with the door open during revs. Should I be able to?

For example if I give it a nice rev up to 4k while in neutral, on the release I'll hear air from the front-middle of the under carriage.

I was a bit concerned at first, but I wasn't sure if it was because I'm not used to it, or something isn't right.

If its a hiss on deceleration, when you let go of the gas, then this is perfectly normal. Modifying any component of the 370Z exhaust has this effect, particularly the cats. If you hear it when revving up, when accelerating then you could have a leak.

You will hear a hissing sound at low RPM. TOTALLY NORMAL. My test pipes hiss like a mo-fo! Esp around 2k

Huh. I think I actually do hear it when accelerating.

How can I absolutely determine if there's a leak and how is it typically rectified?

Thanks for this info!

Do you hear the hiss when accelerating too?

No acceleration hiss

Some of the older VQ35 engines used in the maxima had four cats, two pre-cats ahead of the normal cat that you'd normally see in an exhaust. I'm not sure why he would say that after having the car up on a lift though, it would be immediately evident that the pre-casts were not present on the 370z.

In my experience, most mechanics will try to convince you that aftermarket parts are a waste if they are not an enthusiast themselves. They are so used to seeing cobbled up stuff that they usually push people away from aftermarket parts. I wouldn't give the guy to much credit because he obviously doesn;t know much about the 370. You've made a good choice and will be very happy with the money that you spent.

That's reassuring, thanks! My only concern right now is the possible hissing\leak during acceleration. I don't always hear it, only if I really step on it and it's between like 3k and 5k before it's no longer audible.

I wish I had other Z owners to hang out with or check it out to see if it's just me not used to the sound or an actual problem :eek:

Vid of the sound or it doesn't sound cool ;)

Also, it might help to hear the sound if possible.

What he said ^

One more thing. And I'm on mobile at the moment. But I revved the car just now and I can actually smell exhaust. Just throwing that out there ... Shouldn't be normal right...?


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I am here: http://tapatalk.com/map.php?syhl2o

It's a new exhaust so it's gonna smell a bit. The hiss is also normal when you put a set of HFCs on the vq37 vhr.

So I have read every post in this thread and now feel compelled to chime in.

In stock configuration you have two pre cats and two main cats. Now, you have a driver side unit and a passenger side unit. Each unit consists of 1 pre cat, 1 O2 sensor and 1 main cat. That O2 sensor is located directly between the pre cat and main cat. It is considered your rear O2 sensor. It is strictly for emissions and does nothing to your Air/Fuel ratios. Your front O2 sensors which are located in your exhaust manifolds control your Air/Fuel ratios. Most people commonly refer to the exhaust manifold as a header.

By going to an aftermarket catalytic converter you will eliminate your pre cats! If the anti fouler on your aftermarket cats are done correctly, you should not get a CEL. To also ensure you never get a CEL, you need to make sure there is no exhaust leaks. Specifically between the exhaust manifold and aftermarket cats.

If you hear a hiss under acceleration you most likely have an exhaust leak. It could be anywhere and what you are hearing is a fluttering sound. If you drive between to large objects, buildings walls, etc... it will be most prominent! The "hiss" under deceleration is completely normal. It is at it's loudest when most or all of the back pressure is relieved.

I think that about sums it up. If you have any questions, please do not hesitate to give me a call.

Thank you, Tony

Interesting, i didn't know they had extra cats on the 370, i'm assuming that the 350 still just has the two cats?

Thanks for the information! I was able to learn something from it.

It is the same on the 350 as well. I know that at first glance it can throw you off. But if you dissect it, you can see that the pre cat is metallic and the main cat is ceramic.

I was actually surprised to see something of that high quality in an OEM part. The bottom line though at the end of the day they are still too restrictive! You know as well as do I that aftermarket cats are well worth the money!

Thanks, Tony

Anytime! As an exhaust manufacturer and vendor, I want to help where I can!

Thanks, Tony

Why don't aftermarket / HFCs have a pre-cat, then?

Ahh, so if you remove the cat section on the 350z, it removes them both?
There's nothing in the manifold? and nothing in the Y pipe?

Because...

pre-cats, or "pup" catalytic converters are there to reduce emissions before the catalytic converters heat up. The down stream 02 sensors aren't heated up and working at this point, either, so it wont throw a CEL if they are missing, and noone (meaning not me) really gives a **** about preventing the tiny bit of pollution experienced before the main cats achieve light off, and eliminating them reduces restriction to flow.

That is correct.