Ok so I have a s4 and recently had the exhaust done. I went with the RB header Bonez cat combo from rx7.com then let it run with the 2.5 inch piping all the way back. Now when I hit about 4k it doesn't jump to 7k like it used to with the stock setup. Did I eliminate the backpressure needed to open the 5th and 6th ports? If so, is it hard to convert to s5 style with the air pump? Some times it'll cut out a little when it's over 4k like the 39k lag but longer and more random and past 42- 44k

 

Did you get the RB header with the back-pressure pipe that connects to your actuators? did you block off the ACV with the provided block off plate? you may have shot yourself in the foot - been there & done that!!

Ramses666

 

Yes. If there is no main cat and split air pipe to go to the aux ports then they will not open. Most will tell you to do the rpm switch mod. I think racing beat makes a header with a back pressure pickup tube to open your ports.

If the system worked before just get the main cat welded back up and hook that split air pipe up again to the aux ports. If you are N/A you are not losing that much HP by putting the main cat back on. I've had a straight pipe to a cat back, no sleeves, tb mod, and ported manifolds and i did not notice much of a loss besides exhaust decibels.

If you do not want cat's in general do the rpm switch mod. You can search the archive for it or there should be some writeups in the tech section. There are other ways to get it done, but i've had some many thrown at me saying it works only to have them shot down/debated by other members who swear by their method is gospel. RPM switch seems to be thumbs up across the board.

My.02

 

Yeah.... what he said.... here's what I did - https://www.rx7club.com/forum/showthread.php?t=748570

I should note that my plastic gas tank thing didn't last and I had a custom pressure tank made.... just put it in today... I had added an s5 vdi to my s4 intake as well so I had double trouble with rpm switches.... I spent some $$$ but I think it was worth it.

Ramses666

 

The cheap and easy way is to just duplicate exactly how the S5 triggering system works. One RPM switch running one emissions solenoid that routes air from the air pump to the aux port actuators works great on my car. The catch is you need to still have the stock air pump.

The pic below shows the solenoid connected to the air pump (welded a small fitting and drilled through the casting) and to the actuator air inlet. The red & black wires run to the driver side headlight area where I mounted my RPM switch and tapped into the tach signal and a 12V source. A couple hours labor and $60 is all it took.

 

Nice.... but if your air pump is gone your up the creek... I thought I was being all smart & stuff & got rid of all that air pump stuff.... it came back & bit me in the wallet.

Ramses666

 

They're even expensive at the junkyard ($30). Ask me how I know.

 

P.s. If you just want the power back over 4k with that exhaust you can take the actuators off and wire the ports open. You'll get that power over 4k back, but will loose lower rpm power and gas mileage will drop.

 

The idea is to have everything work correctly with out sacrificing power right? That's where I was... it can be done.

Ramses666