Would it benefit me any to hollow the cat out? If so, how would I do this? Any special tools needed?

 

unless the cat is already non-functional, i'd recommend just getting a replacement race pipe or resonated midpipe setup (your choice).

 

Any suggestions on which to get? Is it a simple bolt on replacement?

 

off the top of my head, you can check rx7.com. however, if you get a quality presilencer, then you should ba able to get it made locally.

 

Get a presilencer. It makes the car sound less horrible with the stock muffler.

 

Bonez race pipe works great.
http://www.rx7.com/store/rx7/saexhaust.html

 

With a straight pipe, or a hollowed out cat, will that make the car loud? I really dont want that, but I would like more power and better mpg.

 

The Bonez pipe is not much louder than stock. Probably adds 10 hp or so. Maybe a little better mileage. Depends on the condition of your cats. If they are clogged the gains will be more significant. Hollowed cat is slightly louder than stock. Straight pipe without some type of resonator or presilencer will be loud.

 

I mean, can you get a straight pipe to just replace where the cat is at? IF so, would that be loud?

Thanks

 

I don't know of anyone who sells a ready made straight pipe. If you have one made be sure to use thick walled pipe like RB and Mazdatrix sell. Normal exhaust pipe will not last long on a Rotary. There are two pre cats and the main cat. You probably want to replace all of them with the pipe. That's what the Bonez pipe does. It also uses a resonator. I've never used a straight pipe, but I'd expect it to be pretty loud without some type of resonator in it.

 

With a stock exhaust manifold and straight pipe in place of the cats it's not really super loud, but it is quite a bit louder than stock. It makes the stock muffler sound kind of gross, too. Sounds much better with a Racing Beat muffler.

 

maybe its just me but i dont think youll gain anything be just hollowing the cat out. Theyre not restrictive unless clogged up anyway.

 

mine was clogged i took it off and grabbed a stick and rammed all the stuff in it out of it and bolted it back on its louder but all you need is a new muffler to make it sound better.

 

How do you know if its clogged up or not?

 

Remove it, hold it up to the light and look through it. There should be a honeycomb structure that you can see light through. A 2' long prybar will break the honeycomb. Careful, it is asbestos based material. You don't want to breathe in the dust.

 

i am also considering punching out the cats in my 84 gsl...i would like to open the exhaust up a bit while still having some backpressure to the system. i'm doing this on a budget right now but plan to get a full headerback exhaust made locally once i have the cash

heres what the plan is far....i would like to hollow out the two pre cats and the primary cat rather putting straight piping in (keeping the exhaust looking stock), then i plan on cutting the stock rusted muffler off and adding either a generic fart can or cheep-o turbo muffler for some sound trials (currently i have one fart can, one super 40 flowmaster, and one dynomaxx that i will try and pick the best sounding) WILL POST VID'S AND SOUND CLIPS

i know that whatever muffler i use will most likely be destroyed soon from the heat....i'm cool with that seeing as i have random used mufflers laying around

i am going to use as much of the stock system as i can right now because i am on budget, is there any resinators or pre mufflers i can eliminate while doing this?

i wish do do this all in one day, so i was wondering how much of a fight it will be to get the whole exhaust system out of the car (with exeption of the manifold)?

any tips on gutting the cats? do all three just unbolt from the system or are they welded onto the pipe?

JUST FYI....i dont have any emmissions i need to pass or restrictions on noise since the car is registered in the middle of BFE :P

 

Don't bother with the Flowmaster. It's been done many times before and it's never once sounded any good.

The cats unbolt from the rest of the exhaust, but you may need heat and PB Blaster or the like to loosen them up if they've never been removed.

 

And there is no reason to attempt to retain any backpressure in the system. That may apply to piston engines, but rotaries just want to BREATHE...


.

 

It's strange how often noobs confuse rotaries with two stroke boingers in that department.

 

I switched to the Racing Beat system, from header to tailpipe. Nice mellow sound at low speeds, more aggressive when you get on the throttle. There's a reason Mazda went to racing Beat to tune some of their models