OPF’s

[Davidpingu]

Had anyone in the UK deleted them successfully and if so how did you do it?
Basically one of the main things I keep reading about the newer models is how much more muted they sound since they started coming out the factory with these and I’d be interested to know if people have done anything to improve the exhaust note

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[Davidpingu]

I think I may have the answer to my own question. These:

https://www.leib-engineering.de/en/leib-opf-deleter/leib-opf-deleter-bmw-z4-m40i-g29

I’m guessing this opens the way to fitting a suitable cat back system if I want to preserve the original rather than gutting it.

Would still be useful to hear of any experiences using these and what exhaust choices people have made

 

[djbilly]

Had anyone in the UK deleted them successfully and if so how did you do it?
Basically one of the main things I keep reading about the newer models is how much more muted they sound since they started coming out the factory with these and I’d be interested to know if people have done anything to improve the exhaust note

I took it to a custom exhaust place and had them do the standard back box mod. They cut it open, take some paint etc or.

It sounds a lot better now, a recommended mod for around £200.

I've got a sports cat going on soon, so guessing that'll also give it a bit more growl.

 

[B54]

Don't you guys have emission checks in the UK? Because removing the OPF probably makes the check fail, I guess?

For me in Belgium this would be a pita to keep swapping exhausts every year.

 

[Tri5tate]

I took it to a custom exhaust place and had them do the standard back box mod. They cut it open, take some paint etc or.

It sounds a lot better now, a recommended mod for around £200.

I've got a sports cat going on soon, so guessing that'll also give it a bit more growl.

can you really modify the downpipe when the OPF is still in place? I heard on some bimmerforums that running catless or high flow cat while still having the OPF can damage then engine as it creates a lot of back pressure and the OPF will get fried. I’m still wondering if there’s any truth to that.
I have a Remus race axle back but still want to increase the volume at bit more so I’m also looking either remove the OPF or running a HF cat

 

[Davidpingu]

Don't you guys have emission checks in the UK? Because removing the OPF probably makes the check fail, I guess?

For me in Belgium this would be a pita to keep swapping exhausts every year.

We do yes. I’ve done quite a bit of research on this and it seems to me like the days of being able to upgrade to a freer flowing exhaust are over. Before OPF’s were around you could still add power and tone with a cat back system and not affect MOT.
Now these things are fitted it looks as though we’re stuck with a strangled and muted car unless we want to risk everything by not having a road legal car. As a consequence it would appear you also risk no insurance payout in the event of an accident.
Sounds like we really are screwed over in the EU and UK now.

 

[Davidpingu]

I took it to a custom exhaust place and had them do the standard back box mod. They cut it open, take some paint etc or.

It sounds a lot better now, a recommended mod for around £200.

I've got a sports cat going on soon, so guessing that'll also give it a bit more growl.

Looks like this is the only option I have to even remotely keep within the law although some are now saying that even noise they are trying to regulate by recording the db from factory.

 

[Sunstorm]

I've got a Milltek filter-back exhaust on mine and it does make an improvment to the sound
but keeps the filter and cat in place. It's not cheap, but it retains the valve so is controlable via the Sport button and should still meet all emmissions regulations.

https://www.fensport.co.uk/products/exhaust-system-milltek-gpf-back-gr-supra-a90

As much as I'd like more power by removing the filter and swapping the cat, I don't think it's worth it when it comes to the MOT.

 

[Davidpingu]

I wonder what just a straight through pipe post OPF would be like. Years ago a back box was mainly there as a silencer and maybe for back pressure but as a person who has a very limited understanding of the dark arts of exhaust systems I do wonder if the exhaust is already quiet and it’s full of back pressure thanks to having something with the equivalent density of a concrete block as an OPF, why the need for a back box at all?!

 

[eliotrw]

I've got a Milltek filter-back exhaust on mine and it does make an improvment to the sound
but keeps the filter and cat in place. It's not cheap, but it retains the valve so is controlable via the Sport button and should still meet all emmissions regulations.

https://www.fensport.co.uk/products/exhaust-system-milltek-gpf-back-gr-supra-a90

As much as I'd like more power by removing the filter and swapping the cat, I don't think it's worth it when it comes to the MOT.

Dont suppose you have a video or anything of the sound do you, hard to find UK examples

 

[Tri5tate]

Dont suppose you have a video or anything of the sound do you, hard to find UK examples

Buy the Remus Race OPF back system if you want a good increase in sound without removing the OPF. Im very happy with it. Unfortunately I dont have any good soundclips.

Although I want even more sound, that's why I bought the Milltek OPF delete pipe now. The OPF doesnt belong on this car. Damn regulations

 

[Davidpingu]

My thinking about whether an EU car needs a back box looks justified.
Looks like Jackie Ding did this which gives around a 20lb decrease in weight in the rear too (back box was about 30lbs)

https://www.tf-works.com/tf-works-a90-toyota-supra-muffler-delete-axle-back-exhaust-race/

Looks like a relatively cheap option too

 

[Sunstorm]

I've not got any recordings of the sound I'm afraid. I might be able to get some in the future, if so i'll be sure to post them up here.

 

[B54]

I've not got any recordings of the sound I'm afraid. I might be able to get some in the future, if so i'll be sure to post them up here.

That would be nice. Thanks in advance! There are almost no sound clips of aftermarket exhausts with OPF, even European aftermarket exhaust video's are without OPF...

 

[Dan]

Someone on the Facebook group had the backbox delete mod and posted a small sound clip and pics of the OEM tips and pipe with joined to a straight pipe.
10th of Jan.
No coding needed and I think the person who done it was also able to keep the valve function in place.

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