R32 GTS (RB20DE) clogged cat

[GabsReDeal]

Hey everyone,

This is my first post apart of the introduction. I tried searching a bit on the forum but couldn't really get a straight answer.

I got the car to my mechanic as I felt it being weak. It seems that it was missing on two cylinders due to the injectors. I had all my injectors clean and the car runs much better. The mechanic also confirmed my suspicions that the cat is clogged and needs to be tackled asap. The cat rattles a bit and the hot exhaust warning frequently lights up when driving after getting the injectors clean.

In my introduction I was asked about what modification I might be interested in and mentioned a cat delete. From what I was told, this is not really beneficial on the RB20DE and there are more cons than pros. 

Could perhaps anyone give some suggestions on what the best course of action would be since the current cat is toast and needs to be removed/replaced anyway?
I can also sometimes smell a strong smell of fuel, but I'm not sure if this is related.

[Duncan]

I'm not sure what sort of shops are nearby, but I'd expect any reasonable exhaust shop could put a cat in it that will not restrict the power that engine makes.

Otherwise, if you want to remove it, short lengths that replace the cat are readily available online, search for "de-cat pipes" or "test pipes"

 

[MBS206]

The hot exhaust light will come on not from just the cat being blocked, but it's just a temp sensor, and it's designed to warn you to not do things like park in long grass.

 

If you've been pushing the motor a bit, it can cause the light to come on.

 

Second if the cat is rattling, I'd suspect it's not blocked, but instead falling apart inside.

 

The easiest "fix" until you can get a cat put back in, is to unbolt your one, bash the rest of the insides out, and then bolt it back in.

 

For a daily driver/street car, I am in agreeance of put a cat in the car.

If it were race car I wouldn't care if it were removed.

[Milkmun]

As above, definitely bash it or get it replaced with a high flow unit.

[GabsReDeal]

Appreciate the feedback. It is street car, but not a daily.

Last week I got a quote from a good exhaust shop for a decat, one which is bolt-on, bolt-off to be easily replaceable. I got quoted for around €150.

On 19/01/2025 at 3:42 AM, MBS206 said:

If you've been pushing the motor a bit, it can cause the light to come on.

I usually do push the motor, but I wasn't in this case to make sure that no damage is done until I get the cat sorted.

I think it's best to also ask the exhaust shop for the other option and see what they can do.

If (big if) I were to decat though, would it be best to tune the car or would the stock ECU handle it? As far as I know, the stock ECU is not tunable and that would require additional purchases.

[GTSBoy]

The stock ECU won't care.

The gains from Nistuning the ECU and then "optimising" the fuel and ignition tables will be about 2 more HP.