[Empire087]

So im not sure i can deal with the drone on my 07 335i, previous owner did a muffler delete, and the drone at 70-85 is awful. I added a set of 20" resonators to help it, but it didnt do much. However it did make it sound pretty solid, reduced the rasp a lot. Is the 3l going to pump too much air for a 3" exhaust? Would probably run 2 resonators, of varying lengths, and then an n1 style muffler in the rear. Currently waiting to install my catless downpipes, which is gonna make things worse, and looking for other options. I considered a 3.5" setup, but its just not a very common exhaust size, and 4" is just way to big.

[cruizinmax]

I have personally seen 700+wheel through 3" exhaust albeit not on this platform. These were on 2.0l 4 cylinders (not that displacement makes a difference here). One of those was a 850whp evo that went to a 3.5" exhaust and picked up less that 25hp. Boost was not exactly the same so hard to say how much of that was from the increased boost.

All that to say, get whatever's convenient. It won't make much of a difference in power if that's the concern.

[Empire087]

Originally Posted by cruizinmax

I have personally seen 700+wheel through 3" exhaust albeit not on this platform. These were on 2.0l 4 cylinders (not that displacement makes a difference here). One of those was a 850whp evo that went to a 3.5" exhaust and picked up less that 25hp. Boost was not exactly the same so hard to say how much of that was from the increased boost.

All that to say, get whatever's convenient. It won't make much of a difference in power if that's the concern.

Yeah, ive run 3" on my prior rb20, and it was fairly quiet. All while sounding good. If i can achieve that id be pretty happy tbh. Again though like you said 2l, But good to know its not that much of a power loss.

[1Bad335turbopsi]

Something like this?

[Empire087]

Originally Posted by 1Bad335turbopsi

Something like this?

Yes actually lol, what do you have going on with that? Also whats the drone like at 2300-3k?

[1Bad335turbopsi]

Originally Posted by Empire087

Yes actually lol, what do you have going on with that? Also whats the drone like at 2300-3k?

3" from the turbo's back and I had the muffler delete with resonator's and it was still too loud this has a lot less drone.

[Empire087]

Originally Posted by 1Bad335turbopsi

3" from the turbo's back and I had the muffler delete with resonator's and it was still too loud this has a lot less drone.

What does the 3" have for a setup? I assume a resonator, no cats, and a n1 style muffler? Looks like i just need to find a 2 into one pipe, and ill be golden.

[_N54]

Would something like this work? https://www.atmspeedshop.com/products/new-exhaust

[Empire087]

Originally Posted by 6266N54

Would something like this work? https://www.atmspeedshop.com/products/new-exhaust

I think these are slightly shorter than a 335i, even my coupe. I think when i do my catless down pipes ill try and make the flanges into something. Shouldnt be too bad.

[1Bad335turbopsi]

Originally Posted by Empire087

What does the 3" have for a setup? I assume a resonator, no cats, and a n1 style muffler? Looks like i just need to find a 2 into one pipe, and ill be golden.

Correct that is pretty much the setup.

[Empire087]

Originally Posted by 1Bad335turbopsi

Correct that is pretty much the setup.

Kind of figured, my rb20 was pretty darn good sounding with that exact same setup. minus the fact that i cant buy a whole exhaust for 200 bucks any more. I just gotta build one instead lol.

[gujukal]

My drone was almost eliminated by making an exhaust cut out on one of the pipes around 50 cm before the end. Try that if you want to save money. Resonators will probably only help if they are installed in the middle and not at the end of the exhaust system.

[neilvan]

stock N54 exhaust diameter is 2.38" x2 pipes, which has an area of 4.43(x2) so 8.86". 3" dia has an area of 7.06".

While single 3" is probably sufficient for most power levels you are going to a smaller area, 3.5" would be more ideal

[Brule]

Comparison between 3 inch dump pipe and twin stockish exhaust with a muffler 6266 .84ar eas 70% wgdc on 26psi boost and 108mph at 200m roll racing. Wastegate screamer pipe

4 inch dump pipe straight 4 inch straight pipe, 6466 1.0ar was 25% wgdc on 26psi and 114mph at 200m roll racing. wastegate plumbed bsck in.

Also changed diff ratio from 3.08 to 4.1

7mph gain less wgdc

Heres some races including 1100hp 2jz Supra, comaro ZL1 and Turbo LS.

[Empire087]

Originally Posted by neilvan

stock N54 exhaust diameter is 2.38" x2 pipes, which has an area of 4.43(x2) so 8.86". 3" dia has an area of 7.06".

While single 3" is probably sufficient for most power levels you are going to a smaller area, 3.5" would be more ideal

If 3.5" was a common size, i would in a heartbeat. I know factory exhaust isnt the best either as far as overall design goes, so that doesnt help it. I so very much want to go single, but i just dont think 3.5" is gonna be it and id like to join the 500+ club. Dont want to build a nice exhaust twice.

[Brule]

3.5 inch is a common size. It would be in all exhaust shops and available off the shelf cats, resonators and mufflers in 3.5 inch.

It will be very loud even with resonators and a muffler.

A stock exhaust will flow enough for 700hp but as I stated above you will just have more backpressure and have a small amount of power loss compared to a 3.5 exhaust.