BMW-style Backbox Mod - first in UK

[nc_]

Hi mate, the video you linked was that in sport and is there even a difference between sport and comfort modes?
I was under the impression the valve opens in sport but that doesn't appear to be the case with ours?

Hi, that was in sport, however with the valve disconnected in the open position. My observations have been that the valve is open on a cold start, then closes after approx 30 seconds, and then opens up at various RPM ranges, rather than being controlled absolutely from the Sport button. I had tried BimmerLink for valve control but it doesn’t work on the Supra, so that’s not an option for full manual control hence disconnecting it.

I’ve been running it since then with the valve open and disconnected without issue. And Toyota didn’t make any comments on it being disconnected (or any fault codes) at its service a couple of weeks ago.

Hope that answers your question! ?

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[gdi2290]

100% make sure you cover the holes in the US version. I only pulled the iInsulation and can hardly tell the difference.

After more research in BMW world the insulation is there to prevent the drone when cruising and you're meant to put it back after

 

[BG500]

Follow up on this one. The US market muffler is different inside. Looks to have a lot more wadding, and a lot less holes. Letting paint dry on it right now, and no pics of my welds cause I am a much better grinder than a welder.

I did cover the few holes that are on the sport outlet side with a 2.75" stainless exhaust strap clamp. Bolted up nice and tight, will last as long as the muffler does.

I don't really think this mod will be worth the effort for US cars. We'll see.

coming back to this, would this mean that the US cars are louder from the factory? I guess less holes means more sound out back? or I'm missing something here?
I'm thinking of doing the mod but would love to have a non-modded muffler as a backup, however getting a used EU spec muffler is probably not even remotely possible (at a reasonable price) so that would have to come form the US.
what do you guys think?

 

[BG500]

any input to this ?
anyone ?

 

[Blue]

Why not just replace the opf with an open pipe and install the leib opf delete sensor.

you can always revert back to the opf part if you want.

i think that will give you more sound.

 

[bigcat]

would this mean that the US cars are louder from the factory?

Yes, compare to the EU spec with OPF, US spec does not have that sh*t.

 

[BG500]

Thanks guys ??

 

[Z4_M40i]

So, inspired by what seems a common mod in the BMW community, I’ve had the backbox modified on my car. I should say this is probably less relevant to US owners, but I chose this mod because I didn’t want the added hassle associated with removal of the cat or OPF/GPF.

We opened the back box, gutted the fibre wadding in there, and replaced the perforated tubing connected to the valved exit with solid pipe, and welded the box back up again.
To me this is how the car should have sounded from the factory. Normal mode has a bit more volume and is more tuneful, while Sport mode brings on a real howl. 40 mile drive home from the garage shows no drone, or negative “day to day” effects of doing this. Pretty good value for the difference made for the price, and a good alternative to a full system requiring a map to account for removing the OPF.
£400 all in for a day’s work felt decent going when a full system seems to push a grand! For those with experience of these vehicles, I would say it’s louder than a 718 Cayman with PSE, quieter than an i30 N in N Mode, and no drone at all

Also, Bimmerlink doesn’t work for the Supra, BimmerCode does, but Link doesn’t - I was going to use this to have manual control of the valve but have just opened it and disconnected it in the open position.

There’s a member local to me on here, so we’ll try and meet up to get a video comparing the stock and the modded.

Hi, could you please share the details of the garage that did the exhaust work? I found a guy in Oxfordshire but he is booked until April.

 

[nc_]

Hi, could you please share the details of the garage that did the exhaust work? I found a guy in Oxfordshire but he is booked until April.

No problem, it’s Underwood Motorsport in Carlisle. Probably a bit of a hike from where you are though!

 

[mwilkinson]

My car was built in Dec 2021 and I'm certain the exhaust has been tamed further. Either that or the factory tune has been modified to reduce the exhaust effect.

The car I borrowed in August last year, which was an early 2021 production date, definately sounded better, especially the burble.

Anyone able to confirm if there have been any factory mods to the UK / Europe cars, or is it entirely in my head?

 

[Davidpingu]

It could just be that the sound will improve marginally as the system cokes up a little more. It won’t be a night and day difference but I don’t know if anything that would have changed between the one you drove and your own

 

[Z4_M40i]

Just got back from pcw, 1 hour and £340 later, my exhaust has been transformed. There is a much deeper tone now, not really a lot louder but you can hear the change. In sport mode with the valve open, there are a lot more pops and crackles on overrun.

In a few years, when the back box needs to be changed, I will definitely look at ac schnitzer or akrapovic, but for now I’m happy with the new sound track at 10% of the cost.

 

[Chappers]

Just got back from pcw, 1 hour and £340 later, my exhaust has been transformed. There is a much deeper tone now, not really a lot louder but you can hear the change. In sport mode with the valve open, there are a lot more pops and crackles on overrun.

In a few years, when the back box needs to be changed, I will definitely look at ac schnitzer or akrapovic, but for now I’m happy with the new sound track at 10% of the cost.

I'm booked in with him in July I can't wait Do you know if he's put you on insta?

 

[Z4_M40i]

I'm booked in with him in July I can't wait Do you know if he's put you on insta?

No, he didnt take any videos, but there is already a supra if you search back a few months.

Your not far from me, avoid the m1 and go via Banbury, much more fun roads

 

[Chappers]

No, he didnt take any videos, but there is already a supra if you search back a few months.

Your not far from me, avoid the m1 and go via Banbury, much more fun roads

Awesome yeah there's a couple I've seen on his page.

Thanks for the advice, me n my mate are going down dropping the supra off then going to go karting lol, how long did it take him to do it?

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