[DennyD06]

Originally Posted by JasW

Well, the Cobb catted are in, but the rasp isn't totally gone. It's not always present at the 4500-5500 RPM range, and when it is, it has less of metallic edge; but it's far from sounding like I've gone and put the stock DPs back in. Not sure if the difference is enough to have warranted bailing on the AR catless (which I will put up for sale shortly).

I'm wondering if I should put the secondary cats back in and lose the Vibrant resonators. For all I know, the secondary cats combined with the primary cats might make a difference.

Damn man .. Sorry it didn't work out 100% for you . I know how frustrating it is. I hated the rasp and the sound was just unacceptable for me . Felt dumb taking a step back from kitty-less dps but taking a small hit from the performance aspect was worth it for me . I'm lucky I didn't have to hack up the midpipes as well for those resonators .

[JasW]

Originally Posted by DennyD06

Damn man .. Sorry it didn't work out 100% for you . I know how frustrating it is. I hated the rasp and the sound was just unacceptable for me . Felt dumb taking a step back from kitty-less dps but taking a small hit from the performance aspect was worth it for me . I'm lucky I didn't have to hack up the midpipes as well for those resonators .

Well, at least it's not out and out horrible as it was before (in that RPM range) and otherwise it sounds good. If I were any good with welding, I'd put the mid-cats back myself, but I have a good exhaust shop that will do it for $125 ... not free, but I'm hopeful it will help. I just hope it isn't worse.

My feeling is the exhaust note in the 335is has been very finely tuned, and any deviation from stock -- even if it's just catted high flow DPs replacing the OEM catted DPs -- screws with the sound. Someone mentioned it's all in the IS muffler, which is plausible since it may resonate differently with the higher flow from either catted or catless. Who knows.

[BSM n54iS]

Originally Posted by JasW

Well, the Cobb catted are in, but the rasp isn't totally gone. It's not always present at the 4500-5500 RPM range, and when it is, it has less of metallic edge; but it's far from sounding like I've gone and put the stock DPs back in. Not sure if the difference is enough to have warranted bailing on the AR catless (which I will put up for sale shortly).

I'm wondering if I should put the secondary cats back in and lose the Vibrant resonators. For all I know, the secondary cats combined with the primary cats might make a difference.

How many miles have you driven with them so far, maybe just give the cats a day or two to break in...? But if not and the rasp is still there b/c of sec cats ..then that really sucks! From everything I've read here our iS exhaust is very fine tuned, and will get very different sound then mods made to either stock or PE/aftermarket.

[JasW]

Originally Posted by Black n54is

How many miles have you driven with them so far, maybe just give the cats a day or two to break in...? But if not and the rasp is still there b/c of sec cats ..then that really sucks! From everything I've read here our iS exhaust is very fine tuned, and will get very different sound then mods made to either stock or PE/aftermarket.

As of this morning, about 60 miles or so. I listened very carefully on my morning drive this morning to the 4 wind outs from a stop I have before getting on the highway, and then a couple after getting off. The first one was pretty much rasp as usual. The next one was no rasp, the third one was rasp only in second at the RPM range inquestion, and the fourth no rasp. Then I had rasp again in 1st after getting off the highway, but not the time after that.

So there is some change/improvement, and it is variable, so maybe it will improve after a day or two more. We'll see! I want to avoid going down the rabbit hole that I've seen others go down in searching for the "perfect" exhaust, putting in a catback, swapping out the mufflers for the Vibrant ultra quiet resonators, changing the exhaust tips, etc. I'm hesitant to even put the secondary cats back for fear it will get worse. And while that's not a horrible expense (and I could put the resonators back), I've already wasted enough money!

[nitehawk]

Originally Posted by Black n54is

How many miles have you driven with them so far, maybe just give the cats a day or two to break in...? But if not and the rasp is still there b/c of sec cats ..then that really sucks! From everything I've read here our iS exhaust is very fine tuned, and will get very different sound then mods made to either stock or PE/aftermarket.

Do you have any rasp with your setup?

[Jam335iCan]

Had significant rasp after going c'less and having secondaries deleted with magnaflow mufflers. Welded vibrant 1792 (1790 would be best) in place of secondaries and the rasp was totally eliminated. Contemplated selling the car because of the rasp...thank god for the resonators.

[BSM n54iS]

Originally Posted by nitehawk

Do you have any rasp with your setup?

I did initially when I finally went WOT on it after 20-30 miles, it was in the mid RPM range..very close to 4500-5500 and was gone before shifting at 6200+. There was a definite resonance to the exhaust note there the first handful of times getting on it, very clinky I remember. But I noticed a definite change to the note on the 3rd day of just starting it up even, just became the deeper grumblier iS exhaust note again and no more rasp...just did a bunch of pulls over the weekend and not a hint of anything nasty.

I think since you noticed an improvement Jas, and on some pulls no rasp..give them some time to break in or to see if it changes to being gone hopefully.

Originally Posted by Jam335iCan

Had significant rasp after going c'less and having secondaries deleted with magnaflow mufflers. Welded vibrant 1792 (1790 would be best) in place of secondaries and the rasp was totally eliminated. Contemplated selling the car because of the rasp...thank god for the resonators.

Yes on either a regular 335i or the PE, resonators seem to be the perfect solution for everybody regarding the rasp of kittyless...and JasW has already been down that road. For w/e reason the way BMW made the iS exhaust baffles resonate so differently seem to be quite particular to change...really making me wonder why they just didn't give us the PE, was it worth it to engineer 3 different exhausts for the same chassis?

[nitehawk]

Originally Posted by JasW

As of this morning, about 60 miles or so. I listened very carefully on my morning drive this morning to the 4 wind outs from a stop I have before getting on the highway, and then a couple after getting off. The first one was pretty much rasp as usual. The next one was no rasp, the third one was rasp only in second at the RPM range inquestion, and the fourth no rasp. Then I had rasp again in 1st after getting off the highway, but not the time after that.

So there is some change/improvement, and it is variable, so maybe it will improve after a day or two more. We'll see! I want to avoid going down the rabbit hole that I've seen others go down in searching for the "perfect" exhaust, putting in a catback, swapping out the mufflers for the Vibrant ultra quiet resonators, changing the exhaust tips, etc. I'm hesitant to even put the secondary cats back for fear it will get worse. And while that's not a horrible expense (and I could put the resonators back), I've already wasted enough money!

Good points. How's the reduction in catless smell for you?

[JasW]

Originally Posted by Black n54is

I did initially when I finally went WOT on it after 20-30 miles, it was in the mid RPM range..very close to 4500-5500 and was gone before shifting at 6200+. There was a definite resonance to the exhaust note there the first handful of times getting on it, very clinky I remember. But I noticed a definite change to the note on the 3rd day of just starting it up even, just became the deeper grumblier iS exhaust note again and no more rasp...just did a bunch of pulls over the weekend and not a hint of anything nasty.

I think since you noticed an improvement Jas, and on some pulls no rasp..give them some time to break in or to see if it changes to being gone hopefully.

That is very heartening to hear. As is the normal, non-raspy windout in that 4-5k RPM range that I get about half the time now. I'm going to wait until next week to see if the pipes "break in" before I decide whether to keep obsessing or give up.

Edit: not only was there no improvement when driving this morning, it also seems as raspy in that RPM range as ever. All this, and I lose 5-10 hp and $$ too! I'm not going to hold out hope that it's going to change, not after having already driven almost 100 miles. You have an MT and you really don't hear anything in that 4500-5500 RPM range in first and second gear anymore? I wind out through that range in 1st and 2nd every time I move from a stop. If I shifted at just past 4000 RPM instead of 6000 RPM, I'd never hear it. But then I might as well give up and get an AT and start playing bingo at the old folks home.

Originally Posted by nitehawk

Good points. How's the reduction in catless smell for you?

Much improved. And gone is smoke from idle revving and after decelerations in stop and go traffic (I always wondered what the person behind me in that kind of traffic must have thought -- a gorgeous IS vert, and he's belching smoke?). The smell isn't 100% gone, though, no doubt due to the mid-cats still being out, but to my nose it's not all that much different than when I was fully stock catted.

[hellokitty]

Any further comments on this? Is the Vibrant 1790 resonators in place of secondary cats the way to go or is it still up for debate for a 335iS?

[mweisdorfer]

Originally Posted by hellokitty

Any further comments on this? Is the Vibrant 1790 resonators in place of secondary cats the way to go or is it still up for debate for a 335iS?

I have the 335is mufflers w/ golf tee mod and have done the secondary cat delete using Vibrant 1792 resonators in their place.

Almost no rasp, at any point, from 550 to 7000rpm

Almost no Hwy drone.

[hellokitty]

Originally Posted by mweisdorfer

I have the 335is mufflers w/ golf tee mod and have done the secondary cat delete using Vibrant 1792 resonators in their place.

Almost no rasp, at any point, from 550 to 7000rpm

Almost no Hwy drone.

Thanks for the tip! You have catless DPs right?

[bmuum3]

What's the difference between 1790 and 1792? I have Macht Schnell DP's and performance exhaust. It sounds great until about 4500 and then it get more and more raspy. Looking to somehow eliminate the raspy.

[mweisdorfer]

Originally Posted by bmuum3

What's the difference between 1790 and 1792? I have Macht Schnell DP's and performance exhaust. It sounds great until about 4500 and then it get more and more raspy. Looking to somehow eliminate the raspy.

1792 are 2.5" wide. You can't use 1790's they are 2.25" wide. The stock exhaust pipes are 2.38" wide or something like that. The muffler shop needs resonators wider so they can just slide it over the stock pipe and weld them on, in place of the secondary cats.

[mweisdorfer]

Originally Posted by hellokitty

Thanks for the tip! You have catless DPs right?

No. I don't. However, tons of forum members, over the years, have done it this way with catless downpipes.

Lots of folks do this -

Catless downpipes + 1792 resonators + X-pipe + BMW Performance Mufflers or 335is mufflers

Note - in the video below. It's a coupe. So, it has an X-pipe. If I'm a betting man, those are P.E. mufflers.

[hellokitty]

Originally Posted by mweisdorfer

1792 are 2.5" wide. You can't use 1790's they are 2.25" wide. The stock exhaust pipes are 2.38" wide or something like that. The muffler shop needs resonators wider so they can just slide it over the stock pipe and weld them on, in place of the secondary cats.

So you should use the 1792 version for coupe and convertibles? Just want to confirm before ordering. I have a 335iS convertible.

[FireBlaze]

Originally Posted by hellokitty

So you should use the 1792 version for coupe and convertibles? Just want to confirm before ordering. I have a 335iS convertible.

Yes 1792 will work. 1790 should too.

[mweisdorfer]

Originally Posted by hellokitty

So you should use the 1792 version for coupe and convertibles? Just want to confirm before ordering. I have a 335iS convertible.

Yep, use the 1792. Also, insist that they use SS 304 piping. They might have to order that in advance.

Bigger is better. If it's too small, you can't do anything with that. They can either fill the gap with slag or make an adapter out of SS piping and then weld it. I'm pretty sure all the coupes, convertibles & sedans with N54 & N55 motors use 60mm pipes, which equates to 2.38-9". So, you need the 2.5" size resonators.

[DYOOS]

I wanted to revive this thread.

I have a 2011 N55 E90 with the PE mod and hi-flow catted downpipes (VRSF). I'm getting some rasp (3500-4k RMPs) and drone (2k-3k RMPs). I'm thinking of putting either 1790 (2.25") virbrant resonators or 1792 (2.5"). Does anyone know if one works better than the other? I'm reading both will work, but 1790 will be more of a seamless fit.

Also, anyone who has gotten this done, what is your experience with drone decreasing and rasp decreasing?

[hellokitty]

Originally Posted by DYOOS

I wanted to revive this thread.

I have a 2011 N55 E90 with the PE mod and hi-flow catted downpipes (VRSF). I'm getting some rasp (3500-4k RMPs) and drone (2k-3k RMPs). I'm thinking of putting either 1790 (2.25") virbrant resonators or 1792 (2.5"). Does anyone know if one works better than the other? I'm reading both will work, but 1790 will be more of a seamless fit.

Also, anyone who has gotten this done, what is your experience with drone decreasing and rasp decreasing?

No rasp with 1792s installed. I also replaced the factory x-pipe with a Magnaflow 2.5" one. Sounds hard ASF

[DYOOS]

Originally Posted by hellokitty

No rasp with 1792s installed. I also replaced the factory x-pipe with a Magnaflow 2.5" one. Sounds hard ASF

You might have a different set up than mine. I'm on an N55 exhaust, so I don't have secondary cats or an Xpipe.

[mweisdorfer]

Originally Posted by DYOOS

I wanted to revive this thread.

I have a 2011 N55 E90 with the PE mod and hi-flow catted downpipes (VRSF). I'm getting some rasp (3500-4k RMPs) and drone (2k-3k RMPs). I'm thinking of putting either 1790 (2.25") virbrant resonators or 1792 (2.5"). Does anyone know if one works better than the other? I'm reading both will work, but 1790 will be more of a seamless fit.

Also, anyone who has gotten this done, what is your experience with drone decreasing and rasp decreasing?

Get the 1792. Trust me