I currently have the Stillen Y-pipe with my stock 97 Cat. Is my cat going to give out pre-maturely or will it last the years that it should. I should mention that I have an RT cat (from NickStam) sitting in a box. If I were to swap cats, would the RT cat pass emissions in 2 years and out last the stock cat? Or will the RT cat not pass and I'd have to switch back to the stock cat in order to pass?

I'm in California and just had my smog check two months ago with a stock exhaust system and passed with flying colors.

 

Have both cats de-clawed or you could get bloody when trying to swap...