i recently bought a 88 GTU it now has the stock exgaust but with mazda installed, super quiet, mufflers. i have read a number of threads on this and many say you need backpressure for the aux ports to open. some say you dont need backpressure at all. some say a multitude of other things about the exgaust. It is so confusing to try and sort through it all for someone who is new to rotaries like i am. so the real question is. can i take those mufflers off and run the car without mufflers or do i need them for backpressure? this is not about new mufflers just about running no mufflers. would doing so cause any other unforseen problems?
OH yeah, i dont know if this changes anything but the car has a mazda installed S5 engine in it.

 

If it truely has an S5 motor and accessories, then backpressure doesn't matter.

 

Having the S5 motor and accessories won't matter, S5s use a signal from the ECU to pressurize the ports. So there's no way the S4 ECU could control them. On an S4, the cats provide the backpressure to open the aux ports, so you could run without mufflers (even though it'll grow tiring in a hurry).

 

Why do you want to run with no mufflers?

 

well i would like to run without mufflers because the ones it has on it currently have absolutly zero sound. i can hear the fan over the engine even at low revs. also i have no money for new mufflers so... i thought no mufflers had to sound better than no sound at all. i dont know if this is the right thing t do but i think i might just try it to see what happens.

 

It'll sound awesome for about 5 minutes, but the first time you have to drive for an extended period of time without them, you'll probably regret it. If you want more sound, but don't have a big budget, you could try something like this if you or someone you know has the tools: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/so-whats-inside-stock-muffler-heheh-867129/

 

Awesome! that sounds like a perfect solution. i have all the tools and the shop to do it in. plus my dad has had 25 years+ of welding experience. thanks man i believe i may look into doing that myself.

 

I wouldn't do it exactly as he has done it. I would personally get a straight louvred pipe to weld in there, and pack it with steel wool.

 

It's not backpressure that opens the ports. It's exhaust pressure. You don't have to have backpressure to get that. Think about that one for a bit!