[paimon.soror]

So this is a bit of an unorthodox ask, but I am in the market for "sound improvement" . So I had been sitting on a catless downpipe from ER for a month or so but decided to let go of it. I wanted the sound and performance, but didn't want to deal with the CEL. I ran catless on my last car, loved it, but always had a pit in my stomach when i had to go to emissions (my tune covered the readiness monitors).

Anyway, I was in the market for an axleback when i came across some good reviews of the Fabspeed. So im going to break 2 rules here, a poll and a list:

1. I'm looking for a slightly more aggressive sound (no drone, but some good WOT feels)
2. Dont want to worry about warranty (CPO for another few years)
3. Dont want to deal with emissions (CT only does an obd2 readiness check)

Here is what i see in my mind:
Axleback:
- Easy install
- Easily reversable
- Sound
- Adds some uniqueness to the car
- No performance, straight up paying for sound

Supercat:
- Slightly more technical install
- Quality cat core HJS
- Haven't seen many reports of CEL from F body owners
- Sound and performance
- Improves turbo longevity (am i right here?)
- Technically voids warranty as it directly replaces an engine emissions control (Dont quote the MWA, it leaves this as a gray area that bmw can easily fight)

Decisions decisions ... especially if im spending this amount of money, so any advice is appreciated!!

[sukhparm.7]

I would go for the axle back (just for the sake of simple install + warranty) but in future if you don't like the sound and want it louder go for downpipes.

[torkles]

dollar for dollar, the money is better spent on the sport cat. you'll actually get a performance increase, and it'll change the sound.

[dr.roro]

I would actually argue that the downpipe is more easily reversible since it’s a straight swap and bolt on. The axle back requires cutting, which you can still reverse with a clamp, but it will be obvious.

Technically both will “void warranty”.

I would go with the Sport Cat DP as it’s a much better value. You get performance and sound — two birds, one stone. Also opens up Stage 2 when you start tuning. No CEL or smell to worry about with the Fabspeed.

[paimon.soror]

Originally Posted by dr.roro

I would actually argue that the downpipe is more easily reversible since it’s a straight swap and bolt on. The axle back requires cutting, which you can still reverse with a clamp, but it will be obvious.

Technically both will “void warranty”.

I would go with the Sport Cat DP as it’s a much better value. You get performance and sound — two birds, one stone. Also opens up Stage 2 when you start tuning. No CEL or smell to worry about with the Fabspeed.

I'm def leaning the sport cat route, but I've read on a few of the forums that unlike other parts that good warranty on that part alone...BMW has been a stickler to make down pipes a full engine void. Again, heresay .

[viperguy212]

Personally I'd go the cat route although I have a hard time justifying the fabspeed price. I get that the quality is excellent and the "no CEL" feature but its a significant markup over other catted options let alone cat-less. Just my $.02.

[paimon.soror]

Ive always heard great things about HJS, they were actually the only ones outside of the OEM cats that would stand up to the heat of Rotary engine exhaust pulses, so that speaks a lot on their longevity.

Ive seen lots of HFC's clog and fail over time

[Josh9167]

Do you have any other mods? I just went through the same debate, but I'm starting from a completely stock car.

I ended up with a FMIC, CP, and Remus Axle back for $100 more than the DP plus install. I'll have to install what I have but I'm not too worried about that.

I'll be getting a tune as well once everything is done.

Edit: if I do t like what I have I'll add the DP later.

[Buse]

I went through the a very similar ordeal. Here's my write-up on it:

http://f30.bimmerpost.com/forums/sho....php?t=1459221

[paimon.soror]

well look at that ... you copy cat!

I think thats a great writeup and a great point. Probably just go ahead with the exhaust for now, and then hold off on the DP until after my CPO/warranty crap runs out. Least amount of hassle it seems.

Also yes, I have a few other mods, a FMIC and CP. So I just dont need to give them more reason to flag me lol

[paimon.soror]

K i committed. Going exhaust. Its not the first mod, its not the last mod. Starting with this ... going to enjoy it, and we will see in a years time (ive only had the car since Nov) how much further i feel like going .

Thanks everyone, you guys have been a big help even though i chose against the popular option.

[4lss]

IMHO Remus axle-back will give you a very small increase in loudness if staying with stock DP. I went with catless after a month of doing the exhaust, it sounds amazing.
I do understand about the CPO situation.

[sirvanny]

What sounds sexier? Mpe with catless downpipe? Or remmus with catless downpipe for a 435i? Opinions?

[Seba77W]

If you're looking for sound I'd go with the axle back. I have the Fabspeed HFC on my 435i and all though the performance improved significantly the sound wasn't much louder. So I picked up the Active Autowerke axle back and it sounds much better. Here's a video.

[paimon.soror]

Originally Posted by Seba77W

If you're looking for sound I'd go with the axle back. I have the Fabspeed HFC on my 435i and all though the performance improved significantly the sound wasn't much louder. So I picked up the Active Autowerke axle back and it sounds much better. Here's a video.

Awesome, thanks for this. So sounds like i made the right choice, starting with the AB and then sooner or later go with fabspeed.