Secondary Cat delete only?

[jml]

Originally Posted by J08M3

The no was directed at the strange comment about buying a new OEM system. I'm confused to why one might have to do this, and why it would have any impact on selling the car?

1) It is a federal crime to tamper with the emission control system (they have to catch you right?, not a big deal)
2) If a primary cat dies (which is not an uncommon issue on M cars), BMW will not give you a new one under the original 80K miles emission control warranty, which means you're buying a new mid section for 3K if you plan to sell the car without being in theoretical legal pickle.

Just my .02

Would be nice if BMW made the center section in 2 pieces.

[J08M3]

I'm pretty sure it's nothing you need to worry about.

[J08M3]

So I take it no one has tried this?

[Blake]

sorry, i've been out of town, still haven't got my camcorder back and taken a video. probably won't be for a few more days.

[z00m]

Installed ,same diameter as pipes, resonators instead of secondary cats, and left second resonators. So 4 resonators. As they don't cut any power-so its free flow from the first cats down. Sound is bit louder and screamer when you push it. Just Perfect
vid:
http://www.sendspace.com/file/3qs4jr

[J08M3]

Nice. How come you chose to put extra resonators in instead of just straight pipe?

[z00m]

Originally Posted by J08M3

Nice. How come you chose to put extra resonators in instead of just straight pipe?

Telling the truth, it was easyer to install resonators then looking for a decent pipe to match. The job was done in 30min. But I think these 4 resonators made the sound I expected on OEM muffler Didn't want it to be too load or even not sexy sound

[bim14]

I don't know too much about the technical stuff with the exhaust of my car. But if I want to make it louder, I would just have to ask a local shop to take out my resonators? and/or secondary cats. What do you guys suggest is the best/safest setup for me to go with. I would change the whole exhaust but it costs too much, and i like the way the stock mufflers/tips look with the car.

[J08M3]

Originally Posted by bim14

I don't know too much about the technical stuff with the exhaust of my car. But if I want to make it louder, I would just have to ask a local shop to take out my resonators? and/or secondary cats. What do you guys suggest is the best/safest setup for me to go with. I would change the whole exhaust but it costs too much, and i like the way the stock mufflers/tips look with the car.

Yep, that should make it a bit louder. Probably not much though.

The reason I'm looking to leave my resonators and only delete cats it I want a more aggressive sound that's slightly louder under hard acceleration, but I don't want it to sound to raspy or to drone while cruising around. If you look at the $1,900+ x-pipe AA came out with it's no different than your stock x-pipe with resonators minus the secondary cat. I'm looking to accomplish the same thing for a very small fraction of the price. Plus according to a number of tuners there is almost no gain by switching OEM primary cat to aftermarket High Flow Cat (costing $1.300) By retaining stock primary cat I won't need to re-flash my ECU (another $1,000) Also, I've yet to get any answers regarding what the HFC's are made out of (ceramic or metallic), I've never gotten a CFM comparison between OEM cat or HFC (only way to prove it flows more). I don't want some cheaply made HFC (probably from china) giving me issues in a couple of years. Exhaust shop eliminating secondary cats should only cost a couple hundred dollars at most.

[J08M3]

I'll be doing this next week, if anyone on Long Island has a video camera and wants to make a couple videos I'll be happy to post before and after clips combined with my Eisenmann Sport mufflers.

[Labrada_Exoticz]

Originally Posted by J08M3

I'll be doing this next week, if anyone on Long Island has a video camera and wants to make a couple videos I'll be happy to post before and after clips combined with my Eisenmann Sport mufflers.

PLEASE do make some before and after videos as I too have been thinking about doing this for a while. G/L

[dogears]

Actually the primary cats are one of the biggest exhaust restrictions. By switching to a higher flow spiral core cat, such as emitec, there is a 8-10 peak hp improvement with more than that gained in the midrange. The trick is finding one that doesn't code.

Originally Posted by J08M3

Yep, that should make it a bit louder. Probably not much though.

The reason I'm looking to leave my resonators and only delete cats it I want a more aggressive sound that's slightly louder under hard acceleration, but I don't want it to sound to raspy or to drone while cruising around. If you look at the $1,900+ x-pipe AA came out with it's no different than your stock x-pipe with resonators minus the secondary cat. I'm looking to accomplish the same thing for a very small fraction of the price. Plus according to a number of tuners there is almost no gain by switching OEM primary cat to aftermarket High Flow Cat (costing $1.300) By retaining stock primary cat I won't need to re-flash my ECU (another $1,000) Also, I've yet to get any answers regarding what the HFC's are made out of (ceramic or metallic), I've never gotten a CFM comparison between OEM cat or HFC (only way to prove it flows more). I don't want some cheaply made HFC (probably from china) giving me issues in a couple of years. Exhaust shop eliminating secondary cats should only cost a couple hundred dollars at most.

[J08M3]

Originally Posted by dogears

Actually the primary cats are one of the biggest exhaust restrictions. By switching to a higher flow spiral core cat, such as emitec, there is a 8-10 peak hp improvement with more than that gained in the midrange. The trick is finding one that doesn't code.

Agreed they are the biggest restriction. Problem is having a cat in the first place. I could definitely see 8-10 hp by eliminating cat all together. Not sure if there's a good HFC out there that will give me 8-10? I don't want to mess with my ECU and have to worry about sending it out to some tuner.

[swamp2]

Good discussion keep it going. I am very interested in gains that can come fairly cheap as well. I also want to avoid fault lights. Cat back systems and mid sections are all just outrageously priced. One reason I am keen on a cut out system. My ideal system is one that:

1. Includes a quiet/loud option such as with a cut out.
2. The quiet option would be the same or ever so slightly louder than stock.
3. Gets you 10-15 hp.
4. Costs < $1000 total.

[Bluesummer]

since I'm not a big fan of raspy exhaust, I know this is the nature of our cars but whatever Z4DAVE has is just way beyond my tolerance. Now I just wonder if deleting the 2nd cats or deleting both the resonater and the 2nd cats would lead to the same result.
________
property Pattaya

[J08M3]

I figure if I cut the secondaries out nice and neat and save them, worst that can happen is I decide to weld them back in. I will still be at only a fraction of an aftermarket bolt on system. I'm gonna have to search for a video camera so I can get before and after clips for everyone.

[dogears]

Why not just have Fabspeed weld in their X-pipe? You coudl save your X pipe and just have it reinstalled..... The Fabspeed X-pipe is freer flowing since there are no cats and resonators, and the pipe is not squished and flattened like the BMW pipe. I was under my car yesterday (we installed the AA pulley) and I noticed a lot of flattened areas in the stock X.

Originally Posted by J08M3

I figure if I cut the secondaries out nice and neat and save them, worst that can happen is I decide to weld them back in. I will still be at only a fraction of an aftermarket bolt on system. I'm gonna have to search for a video camera so I can get before and after clips for everyone.

[J08M3]

Originally Posted by dogears

Why not just have Fabspeed weld in their X-pipe? You coudl save your X pipe and just have it reinstalled..... The Fabspeed X-pipe is freer flowing since there are no cats and resonators, and the pipe is not squished and flattened like the BMW pipe. I was under my car yesterday (we installed the AA pulley) and I noticed a lot of flattened areas in the stock X.

Still costs a lot more money than what I'm doing. Plus I want the resonators to remain, they don't cost any power and should help eliminate any drone and keep it from being to raspy sounding. I know the OEM has quite a few squished and flattened spots, but I'm not expecting much difference in HP by eliminating that. My main concern with this mod is better sound, any added HP by losing the secondary cat restriction will just be an added bonus.

[dogears]

Gotcha.... That would be easy to do IMO.

How do you like the Eisenmann Sport? Have you compared it to any other systems?

Btw, do a pulley.... Works great!

Originally Posted by J08M3

Still costs a lot more money than what I'm doing. Plus I want the resonators to remain, they don't cost any power and should help eliminate any drone and keep it from being to raspy sounding. I know the OEM has quite a few squished and flattened spots, but I'm not expecting much difference in HP by eliminating that. My main concern with this mod is better sound, any added HP by losing the secondary cat restriction will just be an added bonus.

[Blake]

stock muffler, secondary cats and resonators deleted with 3" h-pipe on dyno. enjoy!

[DevJ]

soundin good blake. did you change your license plate?

[Blake]

Originally Posted by DevJ

soundin good blake. did you change your license plate?

Yea, got sick of PWNT, opted for the name of my company.