Run test pipes. They're your best option. Add foulers if you throw a check engine light. As long as they don't do a visual inspection you'll be fine and you'll have more sound and more performance. Someone might be able to chime in on it, but would resonated test pipes visually pass as cats? That would be an option as well, possibly.

No washers. No. Stop. Please

 

Washers

 

no one makes ugly test pipes so i doubt it, they are all stainless usually. very diff visually.

 

Thanks guys i think im just gunna get the test pipes b/c im pretty sure i got my emissions done recently and where i live they just do the plug so i think ill be safe.

 

arsehole! never ask such a dumb question! just buy topspeed or whatever for 400$! save yo cheddar young boy and learn!