Anyone running aftermarket catalytic converters? (m30)

[gale]

I've been running the Hartge header system for 2 weeks now without the stock cats. I just have the temporary 16" "test/evaluation" straight pipes between the end of the downtubes and the inlet of the stock resonator.

I've been looking into a pair of compact universal aftermarket cats to weld some flanges on & bolt into the system to make it legal. Anyone have experience with "Car Sound" Magnaflow cats or similar aftermarket universals? They're nice & compact and will fit perfectly and are cheap.

The new headers are plently loud with the stock resonator & rear exhaust so I won't be going to an aftermarket exhaust anytime soon. The stock cat won't work with the new headers and I don't want to butcher them lest I need to put the cast iron headers & stock cat back in if the emission Nazis get pissy with me the next time the emissions test is due.

[Kalevera]

Don, I've installed the Car Sound cats as part of the UUC Corsa exhaust that goes on our 750iL 6 speed conversion cars. They work great. I think one is good for ~ 350 rated HP, and it'd be my personal choice. We've also got one on the parts runner, a Blazer...Passed emissions with no problems, which is a feat for a neglected, salvaged, rusty 130,000+ mile chevy anything.

best, whit

[stx133]

the sound is not just the new headers, the lack of cats will make a large difference to the tone from the pipes. you may reconsider aftermarket exhaust after fitting the new cats.

[Martin in Bellevue]

Don, I had a stock cat flanged to fit my rd headers. The setup is as quiet as stock everything. It does not pull as well as the 'just headers to get to the muffler shop', but the stock cat is quiet & heavy.
The new flanges are rather harsh, angled up with acute bends to the long tube extractor tubes.
I question the ability of the average state emissions guy to notice headers underneath the stock air filter box on an m30.
Did you ceramic coat the headers? It seems to keep the temperature down to very nornal on my tubes.

[ryan roopnarine]

anyone know how much the car sound people want for a set of their cats? (any of the 9000 series)...i tried finding prices for their 2 in 2 out or their smaller units that could be put side by side, but that isn't given over the internet.

[gale]

anyone know how much the car sound people want for a set of their cats? (any of the 9000 series)...i tried finding prices for their 2 in 2 out or their smaller units that could be put side by side, but that isn't given over the internet.

Ryan,

There are many aftermarket outfits that sell the universal 53004 single CarSound/Magnaflow cats in the 4" round style in the $55 +/- range such as:

www.hottexaust.com
www.ajusa.com
Summit Racing, etc.

I ended up getting a Magnaflow 2" dual-in/dual-out #94008 which is the universal replacement for a 535i/735i, for $80 from AJUSA. I coundn't get any spec's on the dimension for the distance between the pipes at end. The overall is 16" which will work fine with a minor alteration in my system. As best as I can tell, the 94008 is the same one they put in their complete stock replacement converter with pipes and flanges. From Car Sound's website, it looks like they're a little too close together by virtue of the angled pipes. Mine needs the centerlines to be 4" apart. I could do it with the 53004's which are 5-1/8" wide but I'd have to tilt them so the seams don't line up and that might look like a kluge to the inspector (most of them slide a mirror under the car to do a visual),

They do have singles with an offset for VW's which would fit nice side by side. The dual will look more factory and I'm thinking with both banks feeding thru the same cat, it will get hotter & burn off the hydrocarbons better.

I'm intrigued with the bitty cats that are for mounting up close to the exhaust ports and wonder if they would flow better and/or do as good a job cleaning the exhaust further away from the ports. Prolly have to make heat shields for them since it looks like they come bare.

Cat-Co makes a less expesive cat that sells in the low $40 range, don't know what their quality is.

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Martin,
My headers are bare stainless. I thought about having them ceramic coated but didn't want to wait to put them on. What do you think about wrapping them instead?

[Martin in Bellevue]

Martin, My headers are bare stainless. I thought about having them ceramic coated but didn't want to wait to put them on. What do you think about wrapping them instead?

I'd suggest ceramic coating. I understand header wrap to trap moisture, shortening their life.

[gale]

I'd suggest ceramic coating. I understand header wrap to trap moisture, shortening their life.

How durable is the ceramic on stainless for repeated heat cycles?

[Martin in Bellevue]

How durable is the ceramic on stainless for repeated heat cycles?

My headers look great. I got the satin gray, here www.performancecoatings.
Walt has had problems with the same ceramic coating, because he has a shop work on his car; once the coating is scratched, things deteriorate. He has watched the headers slide across the garage floor.
The ceramic coated headers seem to keep the heat within the tubes. There are no signs of heat problems from the headers on my car. With the flanged stock cat, the car seems to be as quiet as a stock 535 too.