Catalytic converters - LS Swap

[Joe-ttcif]

Hi,

I have a LS swapped BMW e90 that currently just has a back box. It's too loud and will not pass emissions at MOT (I know, I tried 😂) so I need to fit cats.

There seems to be a huge range of cats out there, varying significantly in price - does anyone have experience with aftermarket cats, preferably on a bigger engine like a large V8 that had to pass emissions come MOT time?

I'll need to fit two but being 6.7l I suspect it will take a lot to pass emissions

Thanks

[E-bmw]

You say you have tried to get it through an MOT & it failed on emissions.

What was the actual failure?

I ask just to know how bad a fail it is currently.

[SturdyHSV]

Joe-ttcif said:

Hi,

I have a LS swapped BMW e90 that currently just has a back box. It's too loud and will not pass emissions at MOT (I know, I tried ??) so I need to fit cats.

There seems to be a huge range of cats out there, varying significantly in price - does anyone have experience with aftermarket cats, preferably on a bigger engine like a large V8 that had to pass emissions come MOT time?

I'll need to fit two but being 6.7l I suspect it will take a lot to pass emissions

Thanks

Whereabouts are you based? If near Newcastle, speak to AAS. They've made a lot of exhausts and supply cats for Monaros and VXR8s etc., so will be familiar enough with LS exhaust requirements.

If a bit nearer London, try Topcats Racing, they're near Aylesbury and have swapped more LS engines into TVRs than I've had hot dinners.

Also, as it's a 6.7 then it's clearly not standard, so along with stroking it, what cam did you put in? Depending on the specs you may be wasting your time entirely even trying to pass emissions, feel free to post them here and can at least give an idea of whether you've got a hope in hell