I have a question about back pressure on RX-7's. I have an 88 gxl N/A and I have a 3" straight pipe, no cat, onto a 3" obx exhaust. I believe that I'm not getting much back pressure, if any at all. What is some ways I can create some back pressure? I was thinking about getting a Racing Beat catback if I cannot create some back pressure. Advice & comments are welcome. Thanks guys.

 

You aren't getting any back pressure because you took out your cat your 5/6 port actuators problably aren't working unless you wired them open.

Put your cat back in so they work.

back pressure on rotaries is not an issue they actually gain more HP when they are free flowing.

However in your case its bad because of the no catalytic converter.

 

3" exhaust is oversized for an N/A, but you can try adding a small pickup tube at the header/exhaust manifold to feed the aux. port actuators.

 

How about if i switch my pipes to 2.5". Do you think it'll help at all?