Can you run catless or hi flow cat with OPF still in place?

[Tri5tate]

Hey.

This is mainy to EU customers, since other markets dont have the shitty OPF filter.
I've heard that running catless or hi flow cat while still having the OPF in place causes backpressure and damages the engine. Has anybody here tried that out or know if there's any truth to that?
I currently have an aftermarket axle back but since the cat and OPF is still in place, the car is still a bit too quiet for my taste. Removing both will probably result in a too loud car. That's why I want to either remove the OPF, or preferably install a hi flow cat to increase sound and power.

So to the question again, has anybody here got rid of their OPF? Did it make a huge difference in sound? And again - can you use an aftermarket downpipe while still having the OPF in place?

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[METAL]

Isn't opf in the cat too?

 

[NitroYellowMKV]

Isn't opf in the cat too?

I think in opf cars it goes downpipe with built in cat, OPF pipes, and then resonator and then backbox or muffler, whatever you call it. I would say you are totally fine running a catless or higher flow catted downpipe. If you are worried about staying legalish, get an AA catted, uses GESI Cats, I know in the USA it is EPA approved, and I think in EU GESI has some sort of approval as well. If you want one, send me a PM

 

[NitroYellowMKV]

Update, so on EU cars with OPF, it is in the location of the resonator on non OPF equipped cars

This is how it looks on NON OPF cars

 

[Tri5tate]

Isn't opf in the cat too?

The OPF is located where the resonator is located on the US exhaust system.
The sensors of the OPF is located in the downpipe though

 

[Extreme Power House]

The OPF is located where the resonator is located on the US exhaust system.
The sensors of the OPF is located in the downpipe though

Got it

 

[Dr. Gaspar]

Hey.

This is mainy to EU customers, since other markets dont have the shitty OPF filter.
I've heard that running catless or hi flow cat while still having the OPF in place causes backpressure and damages the engine. Has anybody here tried that out or know if there's any truth to that?
I currently have an aftermarket axle back but since the cat and OPF is still in place, the car is still a bit too quiet for my taste. Removing both will probably result in a too loud car. That's why I want to either remove the OPF, or preferably install a hi flow cat to increase sound and power.

So to the question again, has anybody here got rid of their OPF? Did it make a huge difference in sound? And again - can you use an aftermarket downpipe while still having the OPF in place?

I'm also interested in knowing if I can keep the OPF and just change to a catless downpipe, but I can't find almost any information. Do you have any news on the subject? thanks

 

[Tri5tate]

I'm also interested in knowing if I can keep the OPF and just change to a catless downpipe, but I can't find almost any information. Do you have any news on the subject? thanks

If its good in the long run i dont know. But a friend of mine has had that setup for a while now without any problem. But I have the cat left and removed the OPF and changed the rear muffler. I think thats the best balance and also doesnt give off the horrible smell of catless. ?

 

[SCZ4]

If its good in the long run i dont know. But a friend of mine has had that setup for a while now without any problem. But I have the cat left and removed the OPF and changed the rear muffler. I think thats the best balance and also doesnt give off the horrible smell of catless. ?

Did you have the OPF delete coded\mapped out?

 

[Tri5tate]

Did you have the OPF delete coded\mapped out?

Yes, I have a custom tune and my tuner removed the code that you will get when removing the OPF. Although you wont get a code right away and it wont put you in limp mode either.

 

[SCZ4]

Yes, I have a custom tune and my tuner removed the code that you will get when removing the OPF. Although you wont get a code right away and it wont put you in limp mode either.

Thanks for confirming. Does removing the OPF greatly improve the sound? Debating that or a catted downpipe.

 

[Tri5tate]

Thanks for confirming. Does removing the OPF greatly improve the sound? Debating that or a catted downpipe.

Yes removing the OPF will give you alot louder bangs sometimes and also open up a more pure engine note. But our european mufflers is also more aggressive than the US variant so I would exhange the muffler as well if I were you.

So either you buy a catback system (HKS, AWE etc) and an adapter ring for our cats. This will give a alot more sound and also retain the catalytic converter. That's the setup I have with a Milltek OPF delete pipe + Remus race axle back muffler. The sound difference vs stock is HUGE.

If you only remove the OPF and keep the OEM cat and muffler the sound will be louder but it will not sound as good as switching to a new catbacksystem. It will be quite a hollow and tin can sound.
If you want really good sound with OEM muffler you must remove the OPF and also switch to a race cat or catless.

 

[geert.bieseman]

Yes you can run with the OPF in place just fine when you have a catless downpipe

 

[Dr. Gaspar]

If its good in the long run i dont know. But a friend of mine has had that setup for a while now without any problem. But I have the cat left and removed the OPF and changed the rear muffler. I think thats the best balance and also doesnt give off the horrible smell of catless. ?

I just don't want to remove the OPF because I don't want to cut the original escape, otherwise the option I would like best would be catted 200 cel and OPF delete. But as I want to keep the original exhaust, the idea would then be catless and leave the rest as it is, but I wanted to make sure it will be a viable option.

in your friend's car, how about the sound? thanks 4 helping ?

 

[Tri5tate]

I just don't want to remove the OPF because I don't want to cut the original escape, otherwise the option I would like best would be catted 200 cel and OPF delete. But as I want to keep the original exhaust, the idea would then be catless and leave the rest as it is, but I wanted to make sure it will be a viable option.

in your friend's car, how about the sound? thanks 4 helping ?

He changed the rear muffler to a Remus and also catless and the sound is lrettt damn loud. But I haven’t heard a Supra with catless and OPF and OEM muffler still in place so I don’t really know how it would sound. But I reckon it will still sound quite hollow and muffled.

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