Stock LS1 VY II Exhaust Manifold/Header and Cats for Compliance

[stephen low]

Gregg

You can't fit any standard extractors worth a damn in these cars anyway, so that's a given anyway. The size of the system may affect emission and noise levels, but as he tests both, if you pass that is what he is looking for.

Provided the cats actually have the ceramic innards and work including the standard electrical connections for start up heating per standard the donor car's standard system, Bernie is not going to argue.

My car runs (when it's running!) a pod filter rather than the stock intake and this is legal. But I have the standard intake MAF and computer and these are the bits that do the most for emissions quality control.

The cat is just an emissions polishing tool, it adsorbs some of the products of combustion, so provided it does just this and knocks your levels down Bernie will not care whose cats you use...Really!!

Bernie will want to see you have cats installed and wired up to a standard controlling system and the newer they are the better. Per above the older they are, the more emission they have previously adsorbed and the less effective they get. Telling Bernie these are brand new or very low mileage cats will get a positive response because they work best new!!

Besides which, I reckon you will need to modify the current system to fit into the engine bay anyway and as they are stainless don't get rid of them unless you have to particularly if they are well made. I had extractors for an RMC modified to fit my GForce, because being essentially the same car I thought they would fit. They didn't but not a question asked at engineering.

Think about it anyway. Or you could talk it through with Bernie, he is very receptive to this sort of communication.

[Plums]

Cats don't have any electrical connections, they get up to thier operating temperature using the heat of the exhaust gas.

From a cold start, the closer they are to the exhaust valve, the quicker they heat up, (this is actually called "cat light-up").
The time it takes for the cats to light-up is crucial in emissions testing. This "cat light-up time" is a hard to get right, as different cats light-up at different rates, cat positioning etc. etc.
In fact, the reason the VYII LS1's had the cats right up close to the manifolds, was to improve thier light-up time to help them pass tighter emmissions controls.