yea thats what i pretty much want to do is just get a cheapo muffler...and have the shop do the rest..i just dont no what to do bout the cats..i want the ports to open up from exhaust pressure not any other way but that..so do i take the two cats out and keep the main cat in......take them all out...gut them all..or what..

 

well stick with the 2.25" exhaust. If you have an S4 the ports are opened via backpressure. If you have an S5 then you need the airpump.

 

i am goin to stick with the 2.25" exhaust but if i remove the cats is there goin to be enough exhaust pressure to open the ports up?

 

Im in Warsaw I would give ya a hand if you wanted. I have access to a full mechanic shop as my dad owns Global Auto. Im 19 as well making next to nothing I know how it is trying to fix your RX-7 w/ no money. I know Montieth here in Warsaw can make custom bends out of whatever size pipe you want. I would get it on a lift and find out what bends and lengths you need and have them do it. There not that expensive if you go in w/ my dad lmao. Grats on getting married.

 

thanks man i appreciate it..i just need to no what i need to do in the exhaust so that the ports still open up the way they need to from the exhaust pressure

 

S5 port actuators run off the air pump don't they? Do the S5 intake conversion then you wont have to worry about the ports opening from exhaust backpressure..they'll just work

 

I have a full s5 intake that i dont want.

 

Besides the built in air pump port actuation, the s5 (1989-1991) intake also has the VDI, which will add a little more power (maybe 6HP above 5000rpm? I dunno). But it's a bit of work to get it to fit onto the s4 (1986-1988). Look up the instructions before you get it.

The ports in the s4 are exhaust backpressure activated. So the more restriction you remove the more likely it is that they won't activate. Typically removing the cat will keep them from opening, since that's where the real restriction (and power potential) is. If you just replace the mufflers you should be fine.

I'm on a strict monthly budget for my car so I fixed it up, maintained it like crazy, saved up for a long long time and finally replaced the old shocks, springs and sways. That way I get increased fun and safety. Shocks are the minimum, but they're most of the cost anyway. My car is way tighter now; it feels solid, instant steering response, rides smooth, steady as a rock, and the limits of road grip are more than I care to test. Next will come mufflers, a cold air box for my lousy hot-air sucking cone, minor weight reduction and - when the old stuff breaks - tires and BBS wheels from a vert and a performance cat with some method of port actuation. Then I'll be pretty much done, though I may experiment a little. Nothing to brag about, just a bit of cheap reliable fun that gets me around.

 

Actually, I always see 2.5 recommended.

Anyways.

If you're on a budget either buy stuff used (make sure you have the split air tube for proper 5th and 6th ports opening) or buy a Bonez race pipe and a Corksport cat-back, nothing gets much cheaper then that for all new stuff.

The race pipe deletes all cats and goes from the manifold to where the rear cat was and the Corksport cat-back with the 2.5" inlet fits.

Or even buy the race-pipe and have the rear section made with a cheap muffler. However this probably will be very loud.

 

http://cgi.ebay.com/ebaymotors/OBX-3...em370021936698

http://cgi.ebay.com/ebaymotors/Borla...em250215245541

http://cgi.ebay.com/ebaymotors/86-92...em360023038288

 

http://cgi.ebay.com/ebaymotors/MAZDA...spagenameZWDVW

I picked up this item and used the airpipe to open the port, and its catless basically. just a st8 pipe