35i: More noise!

[neverender]

Firstly, massive apologies if this has been answered before.
I've spent literally weeks searching forums, Google, and YouTube but turned up very little. I'm thinking I can't be the only 35i owner in this quandary!

Id like to extract a bit more noise, but mainly add more character/drama to the 35i in the form of overrun burbles and upshift cracks. The stock exhaust is great at full chat, but otherwise a little underwhelming coming from an (admittedly artificially enhanced) MPE-equipped M135i, or even the 35iS.

Importantly, I don't want to turn the zed into something unpleasantly loud and yobbish, nor ruin it with drone on my daily commute - just enhance its character. This may or may not be realistic.

To my mind there are few options and I'd be interested in people's experience, or thoughts, on the following:

- After market full system: basically ruled out, due to a combination of lack of availability for the 35i and (more crucially) eye watering cost!

- Another option would be a custom exhaust, but the unknown sound and possible quality issues put me off.
Lopping out secondary cats is an option too, but this introduces other complications.

- Back box delete / alteration: this is probably my preferred route at the moment as it has minimal impact on the OEM-ness of the car, but examples of people doing it, and the resulting sound, seem few and far between. Will it ruin the car? Answers on a postcard.

- Find 35iS backboxes: bit of a long shot to find and likely to be disproportionately expensive compared to cutting open and welding the existing system.

- Just leave it alone you child: enjoy it for what it is, or buy a Subaru with a melon cannon if it bothers you that much.

Knowledge appreciated!

[Smartbear]

Hi, have you tried the golf T mod?
Rob

[Hunter]

Has anyone tried sleeving the rear cans ?

[neverender]

Hi, have you tried the golf T mod?
Rob

Hi Smartbear.
Yes (should have said) but I found it made very little difference. It's currently un-tee'd now though.

[Twin Turbo]

Replace downpipe, cost about £400?
Or have you looked at PCW Exchausts?


To be honest I found my M2 so underwhelming, did not feel special what so ever.

However, replacing the downpipe transformed the car.

[Nick9one1]

The cheapest method would be to use MHD. The base software is £80, and maps are £50.

If you just want a nice burble and dont want a remap, you can flash the stock map and still have access to all the burble settings for £80.

screen-5.jpg (41.42 KiB) Viewed 1460 times

The latest version lets you set different burble settings for standard and sport mode.
The 'aggressiveness' setting lets you chose from a barely audible burble to a group B rally car.

If you go down the exhaust route I'd suggest a front de-cat - you can buy a bolt in replacement part. no cutting or welding needed. It also has the advantage of being 'Invisible' to MOT testers. This isn't an issue at the moment, but the rules might change for petrol cars like they did for Diesels this year.

[R.E92]

and I'd be interested in people's experience, or thoughts, on the following:

- After market full system: basically r

The Z4 has burble enabled by default in the stock BMW tune. It has a duration of 1.25s in normal mode and 2.5s in sport and sport+. It was an option designed for cars that cut fuel injection on overrun like the 135i and 335i. Only the Z4 35i, 35is and 335is continue injecting fuel on overrun so don't need that tickbox.

MHD will let you make it more aggressive so it will give you extra pops and bangs.

I think the best way of getting more exhaust noise would be catless downpipes. It would require an ECU remap with MHD to code out the error but the plus side is you would gain an extra 100bhp.

[sunnydays]

+1 for MHD, the burble option makes it sound amazing!

[Hunter]

Why do people talk about decats when all you have to do is sleeve the rear cans? Doing this increases the volume and gives you all the pops and bangs you could wish for..well it does on other makes of cars i have seen it done to..never heard of it being done on a Z though........

[Smartbear]

Why do people talk about decats when all you have to do is sleeve the rear cans? Doing this increases the volume and gives you all the pops and bangs you could wish for..well it does on other makes of cars i have seen it done to..never heard of it being done on a Z though........

A decat is going to unlock a lot more power than any rear silencer mod
Rob

[R.E92]

Why do people talk about decats when all you have to do is sleeve the rear cans? Doing this increases the volume and gives you all the pops and bangs you could wish for..well it does on other makes of cars i have seen it done to..never heard of it being done on a Z though........

A decat is going to unlock a lot more power than any rear silencer mod
Rob

Exactly. Messing with the silencers will just give you some noise, changing the downpipes will lower back pressure on the turbos which will not only help them last longer but give you more power and a faster spool.

[gwatson]

Exactly. Messing with the silencers will just give you some noise, changing the downpipes will lower back pressure on the turbos which will not only help them last longer but give you more power and a faster spool.

No issues with MOT emissions? Which down-pipes come recommended? Assume they need to be imported from the US? Prices seem to range from £400 (VRSF) to £1800 (Supersprint)

[R.E92]

Exactly. Messing with the silencers will just give you some noise, changing the downpipes will lower back pressure on the turbos which will not only help them last longer but give you more power and a faster spool.

No issues with MOT emissions? Which down-pipes come recommended? Assume they need to be imported from the US? Prices seem to range from £400 (VRSF) to £1800 (Supersprint)

No issues with emissions. I'm not up on what downpipe fitment the RHD Z4, hopefully others would chime in on that. VRSF have a good rep for LHD markets.

[Hunter]

The sleeving of rear cans would cost about £20 and the OP wants more noise not power...............

[Smartbear]

The sleeving of rear cans would cost about £20 and the OP wants more noise not power...............

Wow £20! Who does it for that? Dlv on here mods the rear silencers (if that’s what you mean by “sleeving?)
I think that’s around £270 for a single silencer though & the 35i has two of them.
Rob