E93 and HFCs

[Tragiclil]

Any vert owners have x-pipes with non-branded HFCs? Do they work well with smell? Or is GESI/HJS the only way to go? I’ve seen many comments that non-branded HFCs have been working fine for many E93 owners. Just don’t want to sit at a red light and get covered in that smell.

[DukeofAlexandria]

No idea about “non-branded” ones, but have tried evolve HFC x-pipe and am currently running RKP HFC x-pipe and I don’t really have issues with smell when the tops down.

It’s a little noticeable on first start and obviously don’t let it run for long in a garage ha, but not bad by most standards.

That being said, if you have an exhaust system, you’ll need to put the stock muffler or a very muted muffler back on…..it is ungodly loud when you pair either one of those with an aftermarket muffler system and it’s going to make your ears bleed above 3K rpm….i literally couldn’t stand it for more then about 3 days before it became unbearable….talking full time exhaust dumps challenger/mustang bad.

-Duke

[M3SQRD]

“Cheap” HFCs are something like Magnaflow. Not sure what a “non-branded” HFC is?

I have a full Akra EVO exhaust (two 100 cell HFCs) and the exhaust smell is minimal inside the car. On my other e92 M3, I have the original (2009) AA full exhaust which at the time used two HJS HFCs (also can run stock cats or no cats) and, again, the exhaust smell is barely detectable while sitting inside the car. Starting the cars in the garage and then going for a decent drive, the garage still has a noticeable exhaust smell after returning from a drive (before backing the cars into the garage.

Having seen quality HFCs fail causing a blockage on one side of the x-pipe and resulting in the failure of a s65, I’d personally recommend using high quality known brand HFCs and having them placed after the forward X position to maximize whp/torque and keeping the HFCs away from the location with the highest temps. The additional cost of a HFC pays off in the long run.

[TboneS54]

The cheap cats liek from magnaflow were not quite good enough in my opinion to kill the smell (and barely passed smog), but that was on my E46 where they were the only cats (in sect 1). So if you're running test pipes or down pipes or whatever you want to call them with no primaries and you're wondering about the smell with just secondaries in the X pipe, no I don't think you'll be ok. If you're running some cheap cats AND a set of factory cats, you'd be ok I'd think. I've read some say no too bad of a smell with just stock secondaries.

What's the point of an aftermarket X pipe? Isn't the stock x pipe pretty perfect? Full 2.5", crossover, quality cats and resonators. With priamrys out of the way and a muffler, the car is plenty loud.

[bipp]

ymmv but I got a ride in RugbyBro's E92 with non-branded cats (fwd X titanium) and Akra rear section. sounded amazing and didn't notice any in car smell. think his cats were in the secondary position. not too loud IMO (for ref, Akra Evo can pass 92db Laguna and there's no reason this setup should fail) but that's partially due to the Akra rear section - I'm likely going down this route for my exhaust setup since it seems like the best combo of everything.

[Tragiclil]

I appreciate the responses. I initially brought this up since I’ve heard from other forums that HFCs that aren’t GESI/HJS essentially do nothing as they’re likely Chinese made. Especially when it comes to smell. So just want to see what other people’s experience are with x-pipes that don’t necessarily have HFCs from GESI/HJS. I haven’t heard good things about smells from Valvetronic or Bomiz HFCs. So is the other alternative only GESI/HJS?

[bipp]

Originally Posted by Tragiclil

I appreciate the responses. I initially brought this up since I’ve heard from other forums that HFCs that aren’t GESI/HJS essentially do nothing as they’re likely Chinese made. Especially when it comes to smell. So just want to see what other people’s experience are with x-pipes that don’t necessarily have HFCs from GESI/HJS. I haven’t heard good things about smells from Valvetronic or Bomiz HFCs. So is the other alternative only GESI/HJS?

The problem here isn't the manufacturer of the cats, the problem here is that Bomiz is an overpriced Alibaba raspy shit tube for easily influenced YouTube audiences. The target demographic doesn't care about cat quality and the manufacturer has no reason to spend an extra cent on quality cats. My friend's Ti xpipe was made in China and I didn't really notice the smell - I'm always been somewhat asthmatic / sensitive to air quality so I think that's a decent litmus test that they are doing something at least. Badly made products are designed by bad engineers, regardless of the place of actual manufacturer as long as they are following instructions.

Akrapovic, AA, RKP, whatever - pick a vendor known for building quality items. Otherwise, if you are very sensitive to the smell, you might be better off keeping the OEM cats and getting a louder rear section (Eisenmann Race for example).

[M3SQRD]

Originally Posted by TboneS54

The cheap cats liek from magnaflow were not quite good enough in my opinion to kill the smell (and barely passed smog), but that was on my E46 where they were the only cats (in sect 1). So if you're running test pipes or down pipes or whatever you want to call them with no primaries and you're wondering about the smell with just secondaries in the X pipe, no I don't think you'll be ok. If you're running some cheap cats AND a set of factory cats, you'd be ok I'd think. I've read some say no too bad of a smell with just stock secondaries.

What's the point of an aftermarket X pipe? Isn't the stock x pipe pretty perfect? Full 2.5", crossover, quality cats and resonators. With priamrys out of the way and a muffler, the car is plenty loud.

Relatively speaking, a forward X placement develops considerably more power than an aft/stock X placement. The power difference of a forward X is noticeable. Also, titanium X-pipes weigh a lot less than a stock X-pipe.

[a5m]

Only if there was a Ti forward X with GESi/HJS cats option...

[M3SQRD]

Originally Posted by a5m

Only if there was a Ti forward X with GESi/HJS cats option...

The BimmerWorld forward X x-pipe with GESi HFCs would be perfect. Dyno plots I’ve seen of their x-pipe shows they put down some serious whp! Unfortunately, unless you are actually building a true track/race car not registered for street use, BW will not sell you their forward X x-pipe. It would be easy to weld in GESi or HJS HFCs if you could get your hands on one of their x-pipes. I know there are versions with HFCs being used. Maybe they’ll show up one day in the FS section of the forum.

The Sub2 Speed House Titanium forward X x-pipe is another option but it’s expensive and no option for HFCs. Plus finding Titanium HFCs isn’t easy and if you do their cost is close to the cost of the Titanium forward X x-pipe. I suppose you could use SS HFCs and clamps to integrate them into the Titanium x-pipe.

[a5m]

Originally Posted by M3SQRD

The BimmerWorld forward X x-pipe with GESi HFCs would be perfect. Dyno plots I’ve seen of their x-pipe shows they put down some serious whp! Unfortunately, unless you are actually building a true track/race car not registered for street use, BW will not sell you their forward X x-pipe. It would be easy to weld in GESi or HJS HFCs if you could get your hands on one of their x-pipes. I know there are versions with HFCs being used. Maybe they’ll show up one day in the FS section of the forum.

The Sub2 Speed House Titanium forward X x-pipe is another option but it’s expensive and no option for HFCs. Plus finding Titanium HFCs isn’t easy and if you do their cost is close to the cost of the Titanium forward X x-pipe. I suppose you could use SS HFCs and clamps to integrate them into the Titanium x-pipe.

Yea bummer on the BW X-Pipe, but it's made by MagnaFlow who I think primarily use 409SS so it gets pretty rusty depending on where you live. I saw one in NJ that didn't look too great.

I've reached out to Sub2 twice and never heard back. It's too expensive anyway, and like you said cats would be a challenge unless you didn't weld them in.

[M3SQRD]

Originally Posted by a5m

Yea bummer on the BW X-Pipe, but it's made by MagnaFlow who I think primarily use 409SS so it gets pretty rusty depending on where you live. I saw one in NJ that didn't look too great.

I've reached out to Sub2 twice and never heard back. It's too expensive anyway, and like you said cats would be a challenge unless you didn't weld them in.

The BW forward x-pipe is made from 304 SS. It’s a custom BW design manufactured by Magnaflow to BW’s specs.

$3k is expensive for a dual resonated forward x-pipe. It better generate more whp than a SS aftermarket x-pipe and, at a minimum, match what the BW forward x-pipe produces. The weight savings is nice but if it doesn’t match whp from other forward X designs then it’s definitely not worth the cost. My Akra EVO exhaust wasn’t inexpensive but, even after 14 years of ownership, I still love it.

[hkspinoyr]

Originally Posted by M3SQRD

“Cheap” HFCs are something like Magnaflow. Not sure what a “non-branded” HFC is?

I have a full Akra EVO exhaust (two 100 cell HFCs) and the exhaust smell is minimal inside the car. On my other e92 M3, I have the original (2009) AA full exhaust which at the time used two HJS HFCs (also can run stock cats or no cats) and, again, the exhaust smell is barely detectable while sitting inside the car. Starting the cars in the garage and then going for a decent drive, the garage still has a noticeable exhaust smell after returning from a drive (before backing the cars into the garage.

Having seen quality HFCs fail causing a blockage on one side of the x-pipe and resulting in the failure of a s65, I’d personally recommend using high quality known brand HFCs and having them placed after the forward X position to maximize whp/torque and keeping the HFCs away from the location with the highest temps. The additional cost of a HFC pays off in the long run.

Has anyone had check engine light after running 100 cell HFC?

[M3SQRD]

Originally Posted by hkspinoyr

Has anyone had check engine light after running 100 cell HFC?

Yes. However, I had rear O2 bungs welded onto my Akra Evo mid-pipe after the HFCs. It was hit or miss whether the CEL came on. The light was on more than it was off. You’ll also get a CEL with 200 cell HFCs. I’ve had to swap back and forth every two years for emissions testing but it’s worth it.

[hkspinoyr]

Did you try o2 spacers?

[PNWVERT]

I am running the Macht Schnell Xpipe with HFC on my E93. I have it paired with the Corsa exhaust. Used it on my Vorsteiner Ti as well. I agree with the rest, it gets loud under throttle. I have yet to install my catless T1R Xpipe si I can add a little more power before tuning.

[a5m]

Originally Posted by PNWVERT

I am running the Macht Schnell Xpipe with HFC on my E93. I have it paired with the Corsa exhaust. Used it on my Vorsteiner Ti as well. I agree with the rest, it gets loud under throttle. I have yet to install my catless T1R Xpipe si I can add a little more power before tuning.

Would love to hear the MS+Corsa combo. Does it drone? You added the cats in the primary or secondary position?

Been looking at the Corsa, it's a underrated system. Probably due to the stupid tips and ugly mufflers, but that can be fixed.