M37 high flow cats....

[beachbum718]

So if you didnt know.i bit my own words and jumped on a brand new hfc made by kinetix.found them for 300 shipped on ebay.seller bought them for his 370z and never installed them.

Anyway after 1 week of driving with them.i can just say wow! What a difference it makes in the m37.the torque and pull of engine is awake now.sound is amazing from 5k on.no drone.no rasp once warmed up...paired with stillen catback and r2c intake.its amazing.inside with windows up.it isnt crazy loud or annoying. Its perfect.just what i wanted.happy i didnt spend 600 on stillen hfc.lol.also.no smell inside cabin.just pure opened up power when you slamm the pedal.my advice if you already have a cat back.
Go buy hfc asap....woke my car up from a deep sleep!

Videos and sound up soon.

[insanex1]

This is probably my next mod, I have r2c with stock exhaust and i'm going to try and add hfc.

[stm37s]

So if you didnt know.i bit my own words and jumped on a brand new hfc made by kinetix.found them for 300 shipped on ebay.seller bought them for his 370z and never installed them.

Anyway after 1 week of driving with them.i can just say wow! What a difference it makes in the m37.the torque and pull of engine is awake now.sound is amazing from 5k on.no drone.no rasp once warmed up...paired with stillen catback and r2c intake.its amazing.inside with windows up.it isnt crazy loud or annoying. Its perfect.just what i wanted.happy i didnt spend 600 on stillen hfc.lol.also.no smell inside cabin.just pure opened up power when you slamm the pedal.my advice if you already have a cat back.
Go buy hfc asap....woke my car up from a deep sleep!

Videos and sound up soon.

So you saying, this part for the 370z will fit our rides? is it street legal? Thanks.

When is the sound clip goanna be ready? lol

[beachbum718]

370z berk,kinetix,fast intentions ,stillen pipes will fit directly. In cali they are illegal. Check your states.ny your fine.it literally took 40mins on install.but i had a lift.

[stm37s]

370z berk,kinetix,fast intentions ,stillen pipes will fit directly. In cali they are illegal. Check your states.ny your fine.it literally took 40mins on install.but i had a lift.

O.k., I will check with my local mechanic to see what the deal is. In Georgia, we have to take an emission test every year to get your tags renewed for your ride, thanks bro.

[insanex1]

370z berk,kinetix,fast intentions ,stillen pipes will fit directly. In cali they are illegal. Check your states.ny your fine.it literally took 40mins on install.but i had a lift.

I got some kinetix hfc also. Did you have to take out your intake to get to the bolts or were you able to do everything from under the hood?

[beachbum718]

You have to loosen them by the upper throttlebody.twist them up.thats what i did.had a friend hold them up while i loosend oem cats and tightened new ones up.100 miles no cel lights.

[stm37s]

You have to loosen them by the upper throttlebody.twist them up.thats what i did.had a friend hold them up while i loosend oem cats and tightened new ones up.100 miles no cel lights.

So when are you going to post a sound clip on how they bruh? lol.

[beachbum718]

I been so busy working this month.ill try this weekend for sure.

[stm37s]

I been so busy working this month.ill try this weekend for sure.

It's all good, I know exactly what you're talking about.

[lKoRTy]

So can someone summarize which hfc will fit on m37/m56 without throwing codes?

[beachbum718]

Kinetix,stillen,berk.i have kinetix hfc over 300 miles no cel.they gaurentee no cels.others dont!video clip coming soon

[lKoRTy]

Are there any pipes available to replace the ones between the cat and near catback? Seems like stillen used to make them for G37's but not for M's?

[beachbum718]

The y pipe? Yea,nope havent found any

[Altered]

The 370z/G37 Y pipes can fit, depending on the design and if you have AWD or not. The Nismo/IPL ones will not unless you run a custom dual setup after the Y. I tried a non Nismo/IPL one on my car, but be careful how you choose. The cheap eBay one sounds horrible. Also the collector size is 3" which is much larger than the remainder of the exhaust so it creates turbulence. Got WD40 everywhere but you can see the size difference in the piping:




This is an area its probably best to just go custom. Most of the quality G/Z catbacks replace the Y pipe section as well.

[rsilva800]

The 370z/G37 Y pipes can fit, depending on the design and if you have AWD or not. The Nismo/IPL ones will not unless you run a custom dual setup after the Y. I tried a non Nismo/IPL one on my car, but be careful how you choose. The cheap eBay one sounds horrible. Also the collector size is 3" which is much larger than the remainder of the exhaust so it creates turbulence. Got WD40 everywhere but you can see the size difference in the piping:




This is an area its probably best to just go custom. Most of the quality G/Z catbacks replace the Y pipe section as well.

^^^This!
The reason a Nismo/IPL will not fit our cars, is because they use a TRUE dual exhaust set up.


Also any aftermarket Y pipe will have a 3 inch collector, those that have an aftermarket exhaust will not have a problem, those that still have the OEM need to take this into consideration.

[Ilya]

Doesn't the Stillen catback exhaust come with the Y-Pipe? Although, not sure if it will work for the AWD guys...TunerzStore lists as only M37/M56 (no mention of 'x'). Stillen's site no longer seems to carry them?

[insanex1]

Got my HFC installed with stock exhaust noticed it has more of a g35 sound to it, a little deeper but not too loud. I did notice once the car is warmed up and i'm idle at a light the left side of the car vibrates a lot. The HFC isn't touching anything wonder if the cat and r2c intake combo is making my idle higher or lower then normal and the ecu parameters can't compensate? They had to take my intake out to install the HFC maybe I need to check everything was put back in correctly.

[beachbum718]

No vibrations at idle...

Have two crappy videos i thought i share anyway.no memory on my phone
Cold start.cold revs
https://youtu.be/OkCw3qhwV_A

Drone test.i drop out of drive into 4th
https://youtu.be/e67hDfNUYQo

[rsilva800]

No vibrations at idle...

Have two crappy videos i thought i share anyway.no memory on my phone
Cold start.cold revs
https://youtu.be/OkCw3qhwV_A

Drone test.i drop out of drive into 4th
https://youtu.be/e67hDfNUYQo

It says videos are private and cannot watch

[beachbum718]

Fixed. Sorry.they suck anyway.i been working all day 24/7. wake up.its dark. get off work, its dark...

[stm37s]

No vibrations at idle...

Have two crappy videos i thought i share anyway.no memory on my phone
Cold start.cold revs
https://youtu.be/OkCw3qhwV_A

Drone test.i drop out of drive into 4th
https://youtu.be/e67hDfNUYQo

It says videos are private and cannot watch

I just got finished watching both of them and pretty cool man.

[beachbum718]

https://www.youtube.com/watch?v=wKUXQ5iccPc

much better video of sound

[Altered]

Sounds good, pretty much like a G37.

[JBHorne]

If anyone is interested in a set of test pipes for an M37, message me. I have a set custom made that I never installed.

[JBHorne]

I also had a custom Y-pipe installed -- installed this along with a Stillen cat-back system. I immediately noticed a DECREASE in performance, especially at low throttle. The factory Y-pipe is a bit restricted, but there is SOMETHING that this does (back pressure perhaps?) which keeps low RPM torque up. I would up removing the custom Y-pipes and reinstalling the factory ones. I still run the Stillen cat back (and also intakes) and love them.

I'd re-install it, but haven't been able to get an explanation as to why a nice and straight Y-pipe had performance issues over stock...

[JBHorne]

Factory system:



Aftermarket Stillen cat-back with custom Y-pipe and test pipes:

[1GR8M56S]

How come no one has just gone straight pipe and eliminate the Y

[armybrat]

I also had a custom Y-pipe installed -- installed this along with a Stillen cat-back system. I immediately noticed a DECREASE in performance, especially at low throttle. The factory Y-pipe is a bit restricted, but there is SOMETHING that this does (back pressure perhaps?) which keeps low RPM torque up. I would up removing the custom Y-pipes and reinstalling the factory ones. I still run the Stillen cat back (and also intakes) and love them.

I'd re-install it, but haven't been able to get an explanation as to why a nice and straight Y-pipe had performance issues over stock...

I wondered about this myself. I found this article so I copied and pasted it:

You certainly can go too big on both exhaust pipes and headers depending on what RPM range you want your torque to peak. However it is not restriction (back pressure) that changes the torque curve rather it is the exhaust velocity. With smaller pipes the exhaust is forced to increase in velocity so when the piston reaches near TDC there will be a scavenging effect from the higher velocity exhaust creating a slight vacuum effect at the exhaust port. If the pipes are too big then the exhaust will be slower so when the piston reaches TDC there will be little or no scavenging effect at lower RPM. The smaller pipes produce more torque at a lower RPM and depending on other performance parameters this may be quite desirable but it is a trade-off in higher RPM power. This trade-off occurs because as RPM, and thus exhaust gas volume increases, the low RPM scavenging effect will be overcome and offset by the added restriction of the smaller pipes. Trading the smaller pipes to bigger diameter, less restrictive pipes can result in power increases in upper RPM ranges due to less exhaust restriction but these too have to be small enough to create enough exhaust gas velocity to create the necessary scavenging effect.

Bigger is not always better and that is why sometimes it can be counterproductive to go overboard on valve sizes, intake runner size and exhaust pipe size. By the same token, smaller is not necessarily better either so the trick is to have a balance of parts and don't go "hog-wild" with the biggest of everything. When someone says that an engine needs a bit of back pressure they are confusing back pressure or exhaust restriction with scavenging. Back pressure will rob an engine of performance but at lower RPM, the scavenging effect created by smaller pipes will make more torque until the exhaust volume reaches the point that enough back pressure is created to cancel the scavenging effect. Back pressure is a power killer and in itself is unwanted so the trick is to balance the pipe size to put the torque where you need it, a smaller pipe will generally give high velocity with good scavenging at lower RPM but at the cost of power robbing back pressure at higher RPM, a bigger pipe will generally give less torque at lower RPM due to lack of scavenging effect but will make upper RPM power as exhaust velocity increases and scavenging is created but without the added restriction of the smaller pipes to create as much back pressure.

The bottom line is that back pressure itself is unwanted and the noticeable increase in bottom-end power that often occurs with a change to smaller pipes/header tubes is due to better lower RPM exhaust port scavenging and not because of added exhaust back pressure these pipes will cause at higher RPM.


The only thing I will add here is this: what little performance gains you get from just doing an exhaust modification (and staying with the stock tune and intakes) will not really be noticeable in a car that is already pushing 330 hp (420 hp in the M56) Most of that will be in the upper RPM range anyway, so unless you are driving at that range all of the time, you won't realize it. When I deleted my Y-pipe and resonators, I went with an X-pipe and stayed with the stock 2" pipe size to the stock mufflers instead of going larger. I feel that this size offers a good balance of low RPM torque and upper RPM power with the stock tune and air intakes...just my $0.02

[JBHorne]

Interesting...I used the term back pressure, but you are correct, scavenging is what I meant. Overall, you can see from the photo above I had the Stillen cat-back kit, a custom Y-pipe, and custom down pipes ready to install. Now I only have the Stillen kit and am very pleased. I would venture to guess Stillen entertained the idea of a full system (including Y-pipe), but elected not to as the Y-pipe probably caused the same issues in their R&D.