Why no High Flow Cats?

[cmuro]

Why does nobody use high flow cats?

I have gone the DP route before on a 350z and the noise was horrible (not trying to hate) as well as the fact you can't pass inspection. Went to high flow cats and was so happy the raspy sound went away, and was able to pass inspection.

I see AR makes a high flow cat but it's like $1k which is a bit ridiculous considering i paid half that for the 350z and that required two pipes.

Am i missing something or is the rasp not there and switching them before inspection once a year is not that much work?

[John Dempsey]

Because high flow cats for our cars still throw codes and are still somewhat restrictive. And expensive

[SANTI21]

The catted AR Downpipe for N55 produce check engine codes ?

[Dackelone]

They sell high flow cats over here. 400 cell and 100 cell units. But yea, they aren't cheap. Most just install DP's and put up with the raspyness. I'm not a fan of the DP route.

[NTTY]

Originally Posted by Dackelone

They sell high flow cats over here. 400 cell and 100 cell units. But yea, they aren't cheap. Most just install DP's and put up with the raspyness. I'm not a fan of the DP route.

Hi, do you some links to share? I'd be interested.
Thank you!

[Dackelone]

Originally Posted by NTTY

Hi, do you some links to share? I'd be interested.
Thank you!

I think I saw some from SKN tuning at the Essen Motorshow a few years ago. They weren't cheap. I think they were included in their stage three chip tuning (flash, intake, exhaust and DP or high flow cats)for 3,600 euros!

[135IS]

Originally Posted by cmuro

Why does nobody use high flow cats?

I have gone the DP route before on a 350z and the noise was horrible (not trying to hate) as well as the fact you can't pass inspection. Went to high flow cats and was so happy the raspy sound went away, and was able to pass inspection.

I see AR makes a high flow cat but it's like $1k which is a bit ridiculous considering i paid half that for the 350z and that required two pipes.

Am i missing something or is the rasp not there and switching them before inspection once a year is not that much work?

you went from a Z to a bmw. things are gunna be a lot more expensive now especially if you want an LSD

[cmuro]

I had the Z a few years ago and believe it or not the aftermarket prices are either equal or less expensive on the BMW parts. You couldn't come close to what the JB4 costs/HP on the Z, there was nothing, even a flash was more expensive and netted you marginal gains. The only way to go big on the Z was either Turbo or Supercharger and with that comes fuel delivery issues and tunes so you are looking at over $10k to get past (granted well past) the JB4 gains.

Actually the LSD is more expensive on the BMW, on the Z it was around $1k for the LSD and then while you were in there you swapped the Final Drive another $1k, plus somebody to put it together was another $600+. I also got a second Pumpkin (Diff Housing) so i could swap back to stock when I sold it, that was about $250 so you are looking at about $3k when all is said and done.

Anyway, I understand the gains aren't as great but not much less than DP and i have to believe the Cat itself isn't that expensive. Hopefully somebody will come out with a cheaper solution than whats on the market now.

[ilikebmxbikes]

Originally Posted by John Dempsey

Because high flow cats for our cars still throw codes and are still somewhat restrictive. And expensive

Pretty much sums it up for most people. It really is a trade off-

Catless
Pros
- most power gain
- costs less than high flow catted
- sound (arguably a con for some)
Cons
- throws a code
- wont pass emissions
- smells like gasoline

High Flow Catted
Pros
- decent power gains
- no smell
- quieter than catless
- will pass smog
- wont throw a code (see con below)

Cons
- cost
- less power gain than catless
- some wear in an throw codes / some do not

[NihonX]

Originally Posted by ilikebmxbikes

Pretty much sums it up for most people. It really is a trade off-

Catless
Pros
- most power gain
- costs less than high flow catted
- sound (arguably a con for some)
Cons
- throws a code
- wont pass emissions
- smells like gasoline

High Flow Catted
Pros
- decent power gains
- no smell
- quieter than catless
- will pass smog
- wont throw a code (see con below)

Cons
- cost
- less power gain than catless
- some wear in an throw codes / some do not

My 135i didn't pass smog when I was running AR Catted pipes but they did keep the car from smelling like ass.

I prefer catted on my 1M even if it isn't AS powerful as catless.
I've had both AR Catted and Catless.

[mikead_99]

I wonder about high-flow cat durability with our higher flow, hotter exhaust. I came from a 350Z myself, with HFC's, and had my fair share of issues with elements rattling in the cats. There were plenty of guys with worse stories, like chunks of cinder-ized cat element blowing out the tailpipes. It seemed like no matter who the vendor was it was only a matter of time before HFC's would fail. I would think our platform would be even harder on them than a NA Z..

[ilikebmxbikes]

Originally Posted by NihonX

My 135i didn't pass smog when I was running AR Catted pipes but they did keep the car from smelling like ass.

i noted in the cons for catted it is sort of hit or miss. there are people with AR's that pass emissions in certain states and others who do not. Some also start out without a code and then after a while wear out a bit.