What is this, Mis-information central?
Cats that "plug up"?
Plug up with what? Go to a tech manual that explains how modern catalytic converters work. They don't "Plug up" or fail in any other way unless there are MAJOR issues with fuel delivery, etc.
3.75% HP increase by removing the cats?
That's 15HP. I doubt you can feel that, seat of the pants. And where is that number from, anyway?
Once again, the gentlemen who started this thread was not interested in you "thinking' you know what your talking about. He wanted specific information, not opinions on weather or not you think Cats can plug up. But just for kicks, I'll explain to you how a Catalytic Converter can plug up.
They are designed to work in a very sensitive environment. They are designed to operate with a very specific air fuel mixture as well as be right at 1200 degrees. Heat kills Cats.... when doing many things, including top speed passes on the salt flats like Patrick, when your engine endures VERY high RPM's for an extended length of time guess what happens.......the exhaust temperature spikes!!! It gets WAY hot! And kills the cats.
For people who have had their cars tuned.....when you have your car tuned for more fuel, all it takes is a few times dumping a little too much fuel in while trying to get the mixture correct and the cats are DONE!
Bad spark plugs throws off the delicate mixture and your cats are done.
Bad spark plug wires....same effect because of weak or no spark.
So as you can see, there are many ways a modern cat can clog.
BTW, 15 is 3.75% of 400, the factory horse power of a C6.......... in case you still didn't figure that one out.......