I inquired about taking my cats off of my 93 RX7. All of you guys said that it would INCREASE boost and that I needed a boost controller. I decided for now to leave the pre-cat on and do the secondary or main cat since I had a straight pipe that would work. I also installed a manual under the hood boost controller. The first thing I noticed was that with the boost controller installed, it seemed that the second turbo wasn't boosting AT ALL. It made an odd swooshing sound. So we took off the controller and just put it back to stock. NOW.....the boost is a tick or two LOWER than it was before I removed the secondary cat??? So with all this talk of the boost supposedly going UP....it seemed to do the exact opposite. Some input would be appreciated!! And I still plan on removing the pre-cat once the new downpipe comes in. Thanks!

 

You probably have a boost leak if you hear a swooshing sound. With boost leaking out you won't be seeing all the boost you should.

Dale

 

behind your intercooler, there is a S shaped rubber hosing that goes to the turbos
check there and go backwards

 

After I took the boost controller off the swoosh sound went completely away and went from NO BOOST when the second turbo kicking it to just boosting a little less once I removed the Cat. I don't think anything is leaking anywhere at this point. The ONLY difference now is that the Secondary cat is off. Thanks!

 

what boost controller did you get?
make sure you have the new solenoid wired properly to the waste gate

https://www.rx7club.com/3rd-gen-archives-73/profec-b-spec-ii-install-review-192249/

 

I don't think manual boost controllers have solenoids :p

 

/facepalm
you are right... that's what he meant
now that I am re-reading his first post....

did he just say he removed the main cat - but kept the pre-cat?
because I know I told this guy to keep the main cat and buy a downpipe in the past

 

I bought a manual boost control, it only has on fitting going to the manifold and one going to the waste gate actuator, nothing high tech or fancy. And I only did the main cat right now becauese the pre cat pipe they sent didn't fit, supposedly the correct one is on the way. So basically with just the main cat off, it appears the boost is SLIGHTLY lower??? Wasn't expecting that.