So some people told me that since my old cats were broken, a cheaper alternative that won’t work thrown a CEL would be HFC’s. So I bought ISR high flows and had them installed. Not only do I have a 430 code and my mechanic says I need spacers to make it go away, but it has a slight hiss when you let off the gas. Anyone else have issues with the ISR? And which spacers do I need to get to fix the issue? Thank you guys
p.s. they did come with gaskets and all the bolts and what look like 2, 90 degree curved o2 sensors but I’m not sure I will link the ones i bought