[edo]

Hi,

I have 'ar design' catless DPs installed. I want to go fully catless as I want to use Stage 3 maps (waiting for a FMIC to arrive). However, I don't want to change the catback as I don't like it loud. The sound is almost perfect for me now.

What are the options?
Change the whole midpipe? To cut out the cats and put resonators? Anything else?
Welding will be needed anyway, right?

Thanks in advance.

edo

[Sniz]

I think cutting out cats and putting in resonators would be fine.

otherwise I think it will be quite raspy.

[edo]

Originally Posted by Sniz

I think cutting out cats and putting in resonators would be fine.

otherwise I think it will be quite raspy.

Thanks.
Can you recommend where to get the resonators from?

[M_M]

your car will rasp and stink as shit if you go no cats.

I did the same and I put the sec cats back on 2 days after.

[Gen_E92]

+1 just keep the second cats...no point getting the extra smell and rasp for 5hp...and the "stages" are flexible, not fixed...just lower the UT slightly if you dont feel comfortable running the second cats on stage 2, although I think you'll be perfectly fine with default setting

[edo]

Well, I got destroyed by E92 M3 and IS-F tonight (will post videos this weekend) and this really sucks. Everyone is telling that one can't get much more power with cats in the exhaust system. Shiv has also written several times that the difference is huge.

Why should it rasp if I put resonators and leave stock catback? I thought that catback and resonators are the most important rasp, noise 'killers'...
And no, the difference is not 5hp between stage 1 and stage 3.

[Craig@SupremePower]

+1...

Originally Posted by Sniz

I think cutting out cats and putting in resonators would be fine.

otherwise I think it will be quite raspy.

[brusso]

let me know how this goes.... I'm in the same boat . I have catless dp's with stock exhaust. Just an idea.... put the i/c in and try running the stae 3 map on the dyno with your current set up. If you are not happy with the results then try removing the secondary cats and redyno the car. The mufflers are not a straight through design and may be the next problem. After all your work you may see only 10 whp difference from removing the cats. All yourmpower will be made from running the stage 3 map ...

[Gen_E92]

Originally Posted by edo

Well, I got destroyed by E92 M3 and IS-F tonight (will post videos this weekend) and this really sucks. Everyone is telling that one can't get much more power with cats in the exhaust system. Shiv has also written several times that the difference is huge.

Why should it rasp if I put resonators and leave stock catback? I thought that catback and resonators are the most important rasp, noise 'killers'...
And no, the difference is not 5hp between stage 1 and stage 3.

Of course not saying the difference between stage 1 and 3 is 5hp. I mean lets say you're on stage 2 now, deleting the second cats will only give u 5-10hp max. The difference is not huge for sure, because they're pretty far downstream and really aren't that restrictive compared to the primary cats. If it doesn't cost you too much to change the second cats to resonators then do it by any means.

[edo]

Originally Posted by Gen_E92

Of course not saying the difference between stage 1 and 3 is 5hp. I mean lets say you're on stage 2 now, deleting the second cats will only give u 5-10hp max. The difference is not huge for sure, because they're pretty far downstream and really aren't that restrictive compared to the primary cats. If it doesn't cost you too much to change the second cats to resonators then do it by any means.

I'm stage 1 now. Stage 2 - only when completely catless. Shiv has told that 100000 times.
Even when I raise UT to 72, performance gets a bit worse. So if I use stage 2 maps, it could be much worse (more aggressive map, default UT settings - 80).

[TheTwinz]

Originally Posted by edo

Well, I got destroyed by E92 M3 and IS-F tonight (will post videos this weekend) and this really sucks. Everyone is telling that one can't get much more power with cats in the exhaust system. Shiv has also written several times that the difference is huge.

Ugh.. I hate IS-Fs. such a shit car. was it a girl driving it? chick car.

[edo]

Originally Posted by TheTwinz

Ugh.. I hate IS-Fs. such a shit car. was it a girl driving it? chick car.

Well, I like the car. And it goes. Neck and neck with E92 M3 all the way up to 275 km/h. And it's a luxury sedan.
A friend of mine (guy) was driving it.

But let's get back to topic. I hate being destroyed... And I need more power.

[newbieman78]

how bad is the smell with just the primary cats removed? I want the AR catless DP's but is the smell that bad or is it only bad when you also remove the secondary cats??

[edo]

Originally Posted by newbieman78

how bad is the smell with just the primary cats removed? I want the AR catless DP's but is the smell that bad or is it only bad when you also remove the secondary cats??

I can't smell anything. Same as with catted DPs.

[scottp999]

Originally Posted by edo

Stage 2 - only when completely catless. Shiv has told that 100000 times.

He has said there is flexibility in those guidlines. If you put hi flow cats in for your secondary cats, then they should flow much better than stock.

You have to do some logging and analysis on the performance at stage 2.

Originally Posted by shiv@vishnu

Stg 1-- stock and mild bolt-on (intake, cat-back, dps, etc,.)
Stg 2-- intake and no cats
Stg 3-- intake, no cats and FMIC

There is some flexibility with those requirements of course. Just don't use a map that is too aggressive for your mods.

Shiv

Originally Posted by edo

Even when I raise UT to 72, performance gets a bit worse. So if I use stage 2 maps, it could be much worse (more aggressive map, default UT settings - 80).

It could be but remember Shiv said that user tourque is not the only thing that makes the stages different.

Originally Posted by shiv@vishnu

Nope. The differences between the maps go beyond the default UT values

Shiv

Stage 1 is for stock and lightly modified cars. I would definitley be "testing" out stage 2 with your mods. My suggestion is to put in hi flow cats so no chance of the smell from fully catless.

One of the DP vendors uses magnaflow high flow cats (model 59959)in their setup, you could look for something similar to fit with the right inlet and outlet circumfrences, like model 59956. http://www.car-sound.com/02product/u...al/599spun.asp

[Sniz]

I did not find that my 335 was that stinky when it was catless.....my m3 was much worse for some reason.

[edo]

Thanks for the info, scottp999.

I'll log runs with stage 1 and 2 maps with different UT settings. Maybe you're right and I'll get better results with stage 2 maps...

[edo]

Originally Posted by Sniz

I did not find that my 335 was that stinky when it was catless.....

Could you smell it inside the car? Or just when you were standing outside next to exhaust pipes?

[ontopofm]

what's the diameter of the stock exhaust pipe? Im thinking of replacing the secondary cats with high flow cats too

[scottp999]

Originally Posted by ontopofm

what's the diameter of the stock exhaust pipe? Im thinking of replacing the secondary cats with high flow cats too

From posts like this one, it says 2.36": http://www.e90post.com/forums/showth...ight=britalman

I would think an exhaust shop could easily fit a 2.5 high flow cat in there.

[golfinz]

What about getting the riss racing mid pipe that just deletes the secondary cats...that piece requires no welding

http://www.e90post.com/forums/showthread.php?t=161070

[Ilma]

Originally Posted by edo

Thanks for the info, scottp999.

I'll log runs with stage 1 and 2 maps with different UT settings. Maybe you're right and I'll get better results with stage 2 maps...

I'm technically a stage 1 having a complete stock exhaust, but I ran the stage 2 maps and did not find any overall change in performance. Stage 2 felt faster seat of the pants but in the end, my times in the FATS test were around 4.5 - 4.6 seconds both on stage 1 and stage 2 maps.

However, stage 2 did leave me with more inconsistent performance (perhaps ongoing part throttle adaptation?) and was not as smooth and fluid as stage 1 is.

So I don't think it would make you any slower.....just might not make you any faster either. If that's the case, then you will know your car is not up to the stage 2 maps.

BTW, I used 75% UT on stage 2 - not the recommended default of 80%.