Ahhh... Stainless has a lower melting point than ceramic... Stainless also has a high expansion coefficient -- repeated flexure leads to breaking. The bits 'n pieces of debris which toasted a Mitsu turbine (which I now use as a desk ornament, mounted on a Manfrotto tripod) were fried bits of stainless... You won't find factory turbos with cats before the turbo irrespective of flow -- it's just not a good idea. If your fuel system runs rich for some reason -- the cat and stuff downstream might get fried. In many states, any alterations to the intake, fuel or exhaust without an Exemption Order are illegal irrespective of the emission numbers. Even if you replace an existing cat, in states like Kalifornia you must show that the cat you are replacing is faulty or has over 50K miles on it. The Smart currently has such low numbers in the US that getting an E.O. isn't appealing to performance shops yet. Many people with aftermarket turbos live in hope that the performance shop which made it will eventually apply for and get an E.O. for their system. Since the E.O. process involves more than one test car with the cars tested over 40K to 50K miles -- I doubt that a performance shop would opt to register and test a turbo configuration with cats ahead of the turbo...
Anyway -- replacing the stock Smart cat with a metallic substrate cat would not achieve legality in most states (specifically in Kalifornia) and moreover would just be more prone to shed particles.
The Beast
The Chick Magnet
1976 Rover Mini
2003 Chevrolet Corvette Z06
2007 Mercedes-Benz E320 Bluetec (SOLD)
2009 smart Passion (Gone)
2011 smart Passion
Today
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