by Swipez » Sun Jul 16, 2017 1:41 pm
To be honest with you, without the "oh if you do this, and this" BS, by deleting the 3rd cat, you will definitely change the emissions, therefore being rendered 'illegal'. There is nothing you can do about that other than paying big money for a professional to sort you out a full exhaust system that can bring you greater performance while maintaining the same emission values. But that just isn't viable for 99% of us.
So let me say this, by deleting the 3rd cat (and if you are running aftermarket headers) you will more than likely get a new rasp tone above 3k rpm that sounds dreadful. If you really want to delete the 3rd cat, I'd recommend doing other supporting exhaust mods while you're at it, including a nice high quality resonator to cut out the unwanted frequencies. I have spent a LOT of time and money on different exhaust set ups on my 3.0L. I have now concluded that having raptor headers>2x hi flow cats>vibrant performance resonator>oval straight through muffler>twin rear mufflers gives me all the added tunable performance and is under the sound limit for nsw road cars of 90db, but still sounds fantastic.
If I were to get emission checked, I'm sure my car would fail as it is flowing far too much compared to stock, and with 200 cell cats. However, the likelihood of me getting referred to a full test like that from a police officer is near non existent, due to how quiet my car is, and I have all necessary parts like cats, mufflers and resonators. So on the side of the road, a police officer wouldn't t be able to defect me unless he had x-ray vision and the ability to recognise cell counts on the fly, which just will never be the case.
Just don't be a wanker on the road and you'll be trouble free 100%.
Hope I've helped,
Jordo.