05-07-2022, 12:59 AM | #24 |
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Guys, swapping the cat on a 540i literally takes 30 mins as long as everything is cool to the touch. I don't know about the 550, but you can reach everything from above and below the car and you don't need to remove anything. That is as long as you have an aftermarket intake.
I'm in California and I've driven the car in both LA and SF with police driving behind me on the freeway and city streets. I can smell the exhaust, but it seems to not bother any law enforcement. For emissions I'm planning on swapping the OEM cat back in and flashing a stock tune. |
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05-07-2022, 08:55 AM | #25 | |
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Mine smells also. I cannot rev in the garage. The entire den area inside will smell of gas. I cannot even begin to imagine how much the catless smell then |
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05-07-2022, 08:57 AM | #26 |
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05-07-2022, 09:28 AM | #27 | |
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05-07-2022, 09:46 AM | #28 |
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catted and catless net the same gains on the stock turbos.
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05-07-2022, 10:55 AM | #29 |
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I'm having a Evolution Racewerks catted downpipe installed this Tuesday. I will be going BM3 stage2. I know by using BM3 it won't throw a CEL. For those that have installed a Evolution catted downpipe when you went through motor vehicle inspection did you pass emissions? Active Autowerke Catted Downpipe claims no CEL any truth to this?
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05-08-2022, 01:21 AM | #31 | |
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In CA, these newer cars should not go through the sniffer, just a simple OB2 read to make sure monitors are on, no CELS, and a quick visual inspection. They will see the DP, but if it looks like the Cat is still there, you'll be good. |
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05-08-2022, 08:12 AM | #32 |
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All dyno's aren't created equal. Too many variables. I'd prefer to see ET & MPH differences.
I know this is like comparing apples to oranges. I put high flow cat's on my Viper. Stock set up was 4 large cats, the high flows eliminated 2 cats and the hi flo cats themselves were smaller units. Probably because of the 512 ci displacement, that was the first exhaust mod that I actually felt a seat of the pants difference. I couldn't believe it. The good thing is that they do their job well and I don't smell any gas. It's louder than hell though...from the factory, there are no mufflers on the car, just resonators. Found a decent video of a M550i downpipe install. Don't mind the dude with the weed shirt. I can't imagine the heat on the top of this thing...between those cats and turbos. No wonder why they had issues with baking oil on the valve stems on the earlier N63's. It's my understanding that baked oil on the stems shredded the valve guide seals and that was why they consumed oil. Last edited by 2022M550i; 05-08-2022 at 08:28 AM.. |
05-09-2022, 05:37 AM | #33 | ||
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I gain 30hp with catted and a tune...Catless is estimated to be an additional 10hp |
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05-09-2022, 05:39 AM | #34 | |
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05-09-2022, 06:44 AM | #35 |
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Yeah, you need to drive for like 30 mins and Start/Stop the car about 3 times. Easiest way to get monitors ready is to drive to the gas station, fill up, go for a nice scenic drive, or a fun little canyon run and by the time you get home you'll be good.
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05-09-2022, 09:02 AM | #36 |
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I have not seen any dyno comparison showing otherwise.
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05-10-2022, 09:01 PM | #37 |
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I got mine Evolution Racewerks catted downpipe installed today and flashed BM3 stage 2. No CEL but there's a noticeable difference from stage 1 to stage 2. There is a slight fuel smell but, I can live with that since there's a nice low end boost in speed. Not much difference in sound from stock so I will most likely install a Dinan catback or if someone can suggest a better sounding catback.... please not too loud.
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05-10-2022, 09:28 PM | #38 | |
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05-11-2022, 07:38 AM | #39 |
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I think the main question here is if you live in an emissions testing state, do the high flow cats even do the job? I can't imagine if you're still smelling gas with the high flows, that they will pass emissions. If they don't do the job, then the juice isn't worth the squeeze and you stay with factory. I wouldn't want to go through that tedious BS replacing those things and swapping them out every two years for emissions testing. If you're in a non-emission state, then go catless….
You guys are lucky, exhaust and tune… And you're all set. In my time, major work was required to get 50 to 75 hp…. Heads, cam, exhaust, intake, fuel injectors, fuel pump, larger mass airflow etc. If you threw a supercharger on there (getting another 75- 150 hp), you almost guaranteed were destroying the engine…. At some point detonation would rear its ugly head. There weren't any knock sensors to retard timing.. and you would either squeeze out a head gasket or put a hole in the pistons….back in my day, I had to walk to school both ways uphill in the rain and snow. |
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05-11-2022, 04:46 PM | #40 | |
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Last edited by BWilson263; 05-13-2022 at 07:58 AM.. |
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05-13-2022, 06:53 AM | #41 |
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I can't speak on any of the G30 High Flow Cats, but I had a 1990 RX7 with a High Flow Cat and passed CARB every time. It did smell a bit, but I never had any issues. This is assuming that you purchased a DP that specifically states it will pass emissions. Usually the more expensive ones will do this. The cheaper ones will pass emissions, but they most likely will not pass CA emissions testing after about a year of use.
I fig that the 550 guys have enough cash to spend on quality high flow cats and would rather go that route if emissions is a concern, due to the complexity of the install. For us 540 guys, its like a 30 min job to swap out DPs. Another thing to consider is whether or not you plan on using any Ethanol blends above E10. Ethanol will coat the honeycomb material in the Catalytic converter and fudge it up. So in that case, a catless DP would be more ideal, although again, the more expensive units will be able to handle this due to them being made of metal. |
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