Cats/ Test Pipes
 

hey guys so i was talking to the mechanic at the nissan dealership near me, which is a friend. He suggested i take the stillen cats off my car. (have a 2012 sport, with stillen SC and stillen exhaust). He said i should put the OEM cats on or test pipes, how much will my fuel milage go down? and how will the oem cats affect the sound i get vs. the test pipes? i do like the sound i have now.

With the SC you should only run OEM cats. Stillen even says this.

yea, they say that you should keep stock cats because you loose boost when you make the exhaust more free flowing on the s/c kit.

I think the problem though is with the cams on the car. Overlap of the cams profiles is the important part. You dont want overlap on a f/i car. (overlap is the length of time both the intake and exhaust valves are open at the same time.) All internal combustion motors rely on cylinder pressure. On f/i cars need only one set of valves open at a time to reduce boost loss out of the exhaust.

What's happening with the Z is you're losing boost with unrestrictive exhausts because of the overlap in the cams. A custom cam would allow you to run more boost, a free-er flowing exhaust and make wayyyy more power.

so best bet is OEM cats then, will i lose noticable HP and TQ and exhaust noise?

So you'll gain power with OEM cats. But you'll lose sound

ill be getting test pipes soon, but i'm not FI so yea lol not even sure why i said that but to lazy to erase all of this -_-