So, I've been watching the threads of the headers by "those 2 companies". Both their headers look great. Could really give a ---- about the complaints in build quality. So I got thinking; how much power could be gained from removing the cats from the factory manifolds?

So, for a little fun, I've decided to modify a stock set that I got a sweet deal on. I got them for $50 shipped, including the O2 sensors. I'm going to drop them off at an exhaust shop and have them remove the cats. Then, I'll lightly clean any steps inside – There are just a couple that I see where the tubes overlap. I was planning to have extrude-hone clean them, but I'm intending on keeping this project well under $400 without dyno time. If the price is right, I'll send them to swaintech for a real ceramic coating. If not, oh well... factory shields will do fine.

This leads me to a bit of confusion. Everyone tells me using O2 spacers will not fool the ECU. However, I see PPE is using them on their IS2/350. Albeit, very long ones. So I plan to go with a similar design. (attached). If they don't work as planned, does the ISF go into limp mode or will it just flash a CEL? And will either of those companies kindly sell me their electronic O2 sims?

 

The cats on the stock manifold are NOT the restriction. The restriction lies within the "log" design. Either way, i'll subscribe to this thread and see what you discover. As for the O2 simulator, you can try calling up "SIKKY" to see if he would be willing to sell it separately as i'm not sure if "Elite" has such a device. Good luck!

 

Sikky wont sell you their Simulator separately. And there is a proven gain from removing all 4 cats. Ill just leave it at that until i get a chance to hit the track.

 

Yeah i'm sure there is a slight gain, but the majority of gains are in combination of cat removal/individual runners.

 

You can't just let the cat out of the bag and leave it. Sounds like you've already gone this route. Fill me in on what you know.