strong bad

(Re-posted as new thread b/c it got hidden in the sticky thread)

So I don't know too much about how this all works...but I was intending on getting the Borla catback exhaust. But then somewhere along the line, I decided I wanted a more free flowing exhaust set up...but I don't know jack about this subject...

I was wondering..can I remove the cats with the Borla installed? Because the whole term, "catback" makes me think it's necessary for the cats to remain...Also, what's this about a mid pipe I've read about? What is its function and is it necessary if you want to remove the cats?

Basically what I'm trying to get at is, what are some options for me to consider if I wanted a free flowing exhaust set up on the car (that may not be street legal)?

What I plan to get so far: RE CAI, Borla catback exhaust...

Thanks...

Koala Joe

Thanks Omicron

Omicron

Nothing gets "hidden" in stickies, they are just where general guestions like this one should go. Otherwise we wind up with 100 like threads when we really only need one.

With regards to your questions, yes, the Borla is a better flowing exhaust than stock. Not a huge improvement, but some. And yes, you can run it without the cat - but you must somehow replace that cat or you'll be missing ~3 feet of your exhaust system! A "midpipe" replaces the cat, and fills this gap, but is not legal for the street.

Exhaust comes out of the Renesis engine exhaust ports and dumps into the exhaust manifold which bolts to the engine block. This manifold can be replaced with a "header" which is a better flowing version of it. Next the exhaust gasses go into the catalytic converter. This too can be replaced with a higher flowing model. The final component is the muffler, and again, it can be replaced with a higher flowing unit. A cat-back muffler just bolts to where the cat ends, or if the cat has been replaced with a midpipe, it bolts to that instead.

HOWEVER, none of these mods will make a huge difference, even when combined, because Mazda did a pretty durn good job of making the factory system low restriction. A header will help most AFTER someone figures out how to regrind the port angles to make the exhaust flow smoothly into it. Next best improvement will be the cat - but at the cost of significantly increased sound. Finally the muffler. Overall you might gain 20-30 HP if you did all mods.

Hope this helps.

JimW

I dont know if the guy driving the car on Rotary performances sound/video clip was trying to get a best time, but I timed his speedo with my timer. 0-60 mph= 8.2 sec, 90+ mph= 12.8 sec. anyway it sure didn't take long to get the car past 90 mph and the catless exhaust system wasn't too loud, I'd still like to get a free flow cat or a large resonator to quiet it down some..... Does anyone think Canzoomers stage 2 will burn out a resonator ? Sorry I don't know much about the internal material of a resonator.

Omicron

My response to this is in the other thread you started.

JimW

Does anyone know if the stock Exhaust has flanges you can unbolt from the cat, as well as the cat having flanges you can unbolt from the exhaust manifold. I need to know so I can bolt the stock system back, in case of warranty issues, Thanks.

MPG > HP

Is this for real? Will the HP gain be spread out across the entire power band on a % increase basis? Where's the parts/vendor/price list?

Omicron

You've gotta keep reading to find the results I'm talking about. My ~30HP number comes from the fact that one vendor claims the mid pipe and exhaust net a 19HP gain, and some intake vendors claim up to 10HP increase from their intakes. These gains are usually available in the mid to upper rev range.

But whether or not these gains are real is the subject of some debate. Racing Beat, who is a very reputable vendor and has been tuning rotaries for a very long time, claims here that no where near 30HP can be gained from intake and exhaust mods alone. While I see their point, I'm not sure that the other vendors would be deliberately falsifying claims either. So the jury's still out on what can really be gained without major engine work. Fact is, Mazda did a pretty durn good job of tuning this car.

Parts currently available for the '8 are all listed in this forum, and link to dyno charts in many cases.

Hope this helps.

Maximus

What issues do you foresee with Greddy and Canzoomer stage 1 together?

brothervoodoo

Canzoomer has recomended both the Greddy and Borla exhausts with Stage 1.