[Bimmer-Bob]

Will they fit BEFORE the secondary cats? Or is this stupid?

Going with catless headers soon. Already have BMW PE and am worried about volume, rasp, and drone. I've already decided to replace stock reso with Borla ProXS muffler, but I don't know if that will do anything for rasp

I get confused as companies seem to interchange the terms "muffler" and "resonator." It seems like the Borla unit basically IS a resonator, as it is a high-flow straight through unit. But if it's not, then I figure I want to be running a reso somewhere, but I don't want to delete secondary cats. I figure I can maybe run two bottle-style resos in series with the secondaries, maybe - is there room? Would it be overkill?

Ultiomate goal is to achieve a similar volume and character to what I have now (stock headers, secondaries, reso, and BMW PE). I could stand a little bit louder, maybe, as long as drone and rasp were dialed down.

[Mike.]

Originally Posted by Bimmer-Bob

Will they fit BEFORE the secondary cats? Or is this stupid?

Going with catless headers soon. Already have BMW PE and am worried about volume, rasp, and drone. I've already decided to replace stock reso with Borla ProXS muffler, but I don't know if that will do anything for rasp

I get confused as companies seem to interchange the terms "muffler" and "resonator." It seems like the Borla unit basically IS a resonator, as it is a high-flow straight through unit. But if it's not, then I figure I want to be running a reso somewhere, but I don't want to delete secondary cats. I figure I can maybe run two bottle-style resos in series with the secondaries, maybe - is there room? Would it be overkill?

Ultiomate goal is to achieve a similar volume and character to what I have now (stock headers, secondaries, reso, and BMW PE). I could stand a little bit louder, maybe, as long as drone and rasp were dialed down.

I feel like thats a hella tight/awkward fit

[MBP0202]

Bimmer-Bob,

I agree with Mike. It's too tight of a fit to put the vibrant resonators before the secondary cats, not enough length of pipe or width to put them in (even if you stagger them they won't work)

Secondary cats in place = no rasp. So you're good there.

Again, you're right on the edge in terms of noise. Catless headers (AA, Mapleridge, SS, MMW) + BMW PE is basically the limit of what normal people can take. Whether you keep the stock resonator or Borla ProXS muffler/resonator won't make too much difference, it will just change the tone of the noise (generally lower pitch.) If you do mostly in town/city driving you might be able to stand it, but if you do primarily highway driving, I would recommend against it. Unless you love to crank the music

I had the mapleridge headers coupled with the BMW PE and I'll admit it was the best sounding exhaust set-up I had. But again, after a while it wore me down, embarrassing if I had company in the car, and I'm getting older so it just didn't fly anymore. Maybe if I was 18 again

Generally the best set-up for the N52 motor is a secondary cat delete (AFE/SS) coupled with the BMW PE. If you need catless headers then keep the secondaries and keep the stock muffler or find the quietest aftermarket muffler you can find.

Good luck with your decision, and just make sure you keep all your stock parts!

[Isaiah5411]

The PE was just too loud for my taste with the top down, so...I added a Vibrant 1794 resonator (3" diameter, 12" long) to my PE where the stock resonator would be in the stock exhaust and it did exactly what I wanted...reduced exhaust volume by 20-25%, reduced rasp significantly and almost eliminated the "drone" experienced when cruising at lower speeds in higher gears. The sound is still impressive but lower in tone and volume. Burbles still present.

I know this is apples and oranges with your situation, but...

[Bimmer-Bob]

Thanks for the input, guys.

Originally Posted by MBP0202

Generally the best set-up for the N52 motor is a secondary cat delete (AFE/SS) coupled with the BMW PE. If you need catless headers then keep the secondaries and keep the stock muffler or find the quietest aftermarket muffler you can find.

Well, I don't have the headers installed yet - but I don't to put them in and then immediately regret the decision, lol.

I had a feeling the Vibrant resonators wouldn't fit in a catted section 1, no big deal there. I definitley want to keep the secondary cats if I do put the catless headers in.

I'm going to keep something in section 2 as well - either the stock resonator or the Borla ProXS. Some other posters led me to think that the Borla unit might actually be quieter than the OEM one, and so I've been toying with the idea of :

AA Headers-Stock Secondary Cats-Borla ProXS Muffler-BMW Performance Exhaust

When you felt like your AA Headers & BMWPE were riht on the edge of too loud, that was with the 328i BMWPE reso delete, right? I've only known of one 1er with AA headers & BMWPE (which maintains OEM reso on our cars), but he also thought it was too loud. Surely it is less loud than 3ers, tho...

I'm confused. I guess I want to have my cake and eat it, too. Really, the sound my car makes now is just about perfect. I could live with some increase, but my interest with headers is much more about power than sound...

[Bimmer-Bob]

I just realized the Borla muffler I'm looking at is 19"x9.5" long - which may in fact be larger (and thus quieter) then the OEM one. Gonna have to measure when I get home - but I think the solution is just to find something as big as possible. From what I hear the Borla ProXS is the quietest high flow muffler on the market.