ItsNiceToBurnRice

Yes one more stupid question for the night. Im the new guy here. 88 GXL NA. I want to cut out cats for a better sounding, cooling running little power boost. But I hear my car needs the back pressure for the 5th and 6th ports to open up, if this is so I have to be extremely careful with what exhaust mods i decide to do right? I mean, all you guys who know your stuff correct me if Im wrong, but if my back pressure drops way to much cant that do some serious damage to my seals eventually? HELP!!!!!!

Splortch

You won't hurt the engine if the actuators aren't working, but they are activated by backpressure (2psi+). You can always wire them open (zip ties work fine, although the front actuator is a PAIN to get at), but you'll lose a bit of low-end torque. Some people whine about the torque loss, but it's perfectly driveable and the high-end power makes up for it. Another solution would be to rig up an electrically-activated port system or steal some air from the air pump with a little T connector somewhere. A more involved solution would be to remove the actuators completely and make block-off plates for the actuators. I'd gut the cats or have a muffler shop put in a single cat (you should be able to get that done for $200 or so with labor). You'll get more power from wired-open 6 ports and a free flowing exhaust than 3 clogged cats any day .

Saku

actually it cost me $130 CDN to do mine...so it should be under $100 US.

Splortch

Yeah, it just depends where you go. I thought $130 CDN was about $15 USD

MasteRX

Yes, gutting your cats will cause your 5 & 6 ports not to work from too little backpressure. Possible solutions are to:

a. Tie the 5 & 6 ports open. This will cause a drop in low end power, but will allow for full power at high RPMs.

b. Gut the pre-cats only and leave the main cat alone. This will reduce the backpressure while still allowing proper operation of the 5 & 6 ports.

c. Gut the pre-cats and replace the main cat with a high-flow replacement. (Catco direct fit available at summitracing.com for $159). 5 & 6 ports work, and you have maximized flow while remaining emmisions legal (yipee!).

d. There are other solutions such as replacing the exhaust manifold and cats with a header/presilencer combo from Racing Beat. (The best power solution of all. Minimal backpressure, has provisions for 5 & 6 port actuation. About $440) Also available is the Bonez cat replacements from RX7.com. They have a nice downpipe with high-flow cat, and it costs around $350. (This is my current setup.)

In conclusion, if you have to pass emmisions, go with option b or c. If you have no emmisions testing in your state, and a sacrifice in low end power is acceptable, then do option c. If you have money to spend then do one of the remedies in option d.

rx7_turbo2

You could also use the pressure from your airpump to open the ports, check around the forum there is a how to on it somewhere.

supergoat

I did that one.