1986 RX-7 S4 13B



I just took off my stock exhaust manifold and there seems to be a 3rd hole besides the 2 exhaust port in the engine (13B). It's about the size of an index finger and located just below one of the 2 primary exhaust ports ( below the rear port, I think).



My point is that I want to get a new header either RB, PS, Cork, etc.

But they all seem to only have the 2 exhaust ports on those header and most of them bolts right up to the engine blocking off that 3rd hole.

So, what does it do? Do I need it?



And yes, I'm running 6 ports...

3rd hole is for the EGR