I believe you are referring to many of the aftermarket cat delete products that are out there in the marketplace. With respect to what happens after that: the less the exhaust has to bend, turn, kink, etc., the better the flow and the higher the power. So YES, an exhaust that leaves the cat area, runs to the passenger side of the differential and then straight out the rear of the car (through a muffler because there is a ton of room under the trunk) is better. You may find that you'll need a single stout muffler if your exhaust is too loud. OR..... you could interrupt the space between the cat and the rear diff and add a second low restriction muffler. There are several out there in many sizes. We have tested several muffler setups and always come back to a two muffler system. One just past the trans and another larger cannister style under the passenger side of the trunk. Again, the straighter the air flow the greater the flow the greater the power. Borla makes some good products. www.summitracing.com sells them in volume at very good prices. These would not be DIY. You'll need to go to a good muffler shop or a performance shop with experienced welders to make this work. You want stainless steel. Mild steel will not last the long haul. Mild steel is cheap if you are not going to keep your car very long. Stainless is the right way to go. A good fabricator with a tubing bender will custom fit the slight bends and turns the PROPER way. You get what you pay for.

A note on race cars. Race cars are looking for performance. They have fitment issues too. Fitment issues (or packaging issues) are the area constraints that an exhaust system has to occupy. Usually these race exhausts are of a larger diameter therefore they take up even more space. Professional racing organizations all have sound restrictions. These are measured in a db or decibel rating. Usually it's around 100 db give or take. Usually the rotary cars (surprise) are the loud cars that push these db ratings. We have failed the test twice and replaced our mufflers with new ones and passed each time. Piston motor race cars usually run just one muffler and it works fine. Like I offer above, they have really straight systems. From the front of the car and engine right out the back. Some cars run them in front of the right rear wheel. This makes for a lighter system and weight on the right side of the car (passenger side) helps offset the drivers weight. All of the systems I know are made of stainless steel (S.S.) All of them use either a race muffler or a high performance street muffler (like I mention above). Most all of these cars DON'T run an under the trunk turn system that turns and bends and has two mufflers. These cars are also way too loud for the street and promote divorce.

Rotary exhaust differences: Heat, heat, heat. A muffler near the engine gets a ton of abuse. We run our cars (and other RX-8 Renesis powered cars do as well) at much higher rpm all the time. All the time. Data shows 5,500 to near 9,000 for 50 minutes. Without caution flags (yellow flags) the min exhaust temp just off the motor is above 1,500F (800+C). This is hot sports fans. Very hot.

Hope that helps. May I suggest you look into any of the zillion exhaust threads out there. Perhaps there are existing products like this that already exist.

 

...relative to what? What was your Baseline Dyno result? ^You to Charles - dyno numbers are meaningless without something to compare them to, like your baseline.

 

I've been so disappointed by the shitty numbers this thing puts out stock.

 

Buy something else then.

 

The car has been out for over 6 yrs now. The capabilities are well known. The time to be disappointed was long ago when Mazda was caught inflating the HP figures.

 

Did you find the internet after buying the car?

 

lolz....

 

Who cares what numbers it puts out? What matters is how it performs. Every time I see somebody review it, they rave about the car as a whole. That to me speaks volumes.

I don't need a car that's fast in a straight line. I want one that handles on rails.

 

^ Amen

 

it's good to get the competitive juices flowing again for 2011, isn't it? Hope your dyno day in Feb is a success man.

 

Just curious; but considering the pains you go to in order to minimize transitions and turns, is there a reason you combine the three runners at all, beyond maybe a crossover pipe? Is it an issue of clearance with the larger diameter piping?

 

I have been reading posts from the RX8 club daily, for hours at a time, even before I bought my car, or became a member, and have never learned so much in one thread.

This EricMeyer sounds like a very smart man and I am very happy to have stumbled across this thread

 

bravo ~!!!

 

It was a long read, but wow, boatload of information.

 

 

Great info