you can gut the cats on a na, but you will suffer on the low end. highway speeds will be better though. dont you ever see this posted here? anyway, get high flow cats, i think they are cheaper than stock anyway. and if you smeel the smell, they are probly clogged. or wait till you put on the greddy and just look at the cats then. you will know if theyre clogged by looking at them. perfect time to put new ones on too.