I'm thinking of doing the muffler delete (otherwise stock intake & exhaust) for running in CS. I don't daily drive the car but the pad is an hour away and if I can avoid getting pulled over I would... but as long as it doesn't go over lets say 95 db I should be fine. I have the following options in order of weight saving:

1) Delete muffler / add an L down-pipe right after (to make sure nothing gets melt / less noise)

2) Delete muffler / Single straight pipe to the back of the car

3) Delete muffler / Second resonator right after / single straight pipe to the back of the car

4) Delete muffler / single glasspack / single straight pipe to the back of the car

I prefer 1) for the maximum weight saving but want to hear from those who have tried any of these.

 

i have #3; it's Chike's old exhaust. it's ~8.5lbs. it's a straight pipe to a resonator with a slight turndown at the end to clear the bumper (center exit). i don't know what the sound level is, but i had no problems passing sound at the events i ran, and I don't believe he had problems at big events with it. it sounds louder in the car than it does outside. i found it tolerable on a daily basis, but it is loud inside. i took it off for the ~9 hour drive to Toledo.

pics from his FS thread: https://www.rx8club.com/rx-8-parts-sale-wanted-44/gauging-interest-b-stock-rx-8-parts-sale-prices-included-183903/

 

I have #5 - The Isley Special.

Event records show it from the mid 80's to the low 90's db-wise.

It is just fine inside the car and no issues on long trips.

IIRC it is 17-19lbs vs. 40 something for the stock setup, but someone might correct me on that.

 

i will say that it's going to depend on whether you are going to be swapping the exhaust every event (trust me, you won't) and/or your tolerance for sound on an every day basis. I'm considering building my own Isley exhaust so I can just leave it on all summer. The extra 10 lbs isn't going to make a difference.

 

Thanks for the thread / pics that helped... As I mentioned the 8 is not a daily driver... I would drive it 2-3 times a month to and from the track / autocross pad. That's why I'm leaning towards the lightest option... and I don't have to tolerate the sound every day.

 

So I took a closer look at the SCCA rules and the exhaust needs to exit either from the rear end of the car or from the side... I guess option 1 is out of the picture. As far as getting a flange goes, is this the right product?
http://www.atkinsrotary.com/store/pr...cat=673&page=1
It doesn't say if it's the 3 bolt or 2 bolt flange or the downpipe.

 

Alright, I went with option 1. It's not as loud as I thought... I would say under 92 db which is our limit at the pad. I will have to check again in a bit and make sure that nothing is getting melt. Here is a video:

http://www.youtube.com/watch?v=nFtlmII1das

 

it has to exit out the side or behind the driver seating position, all the way out the rear is not required

a well tuned and properly operated RX-8 can hit over 100 dB at full song under certain conditions with a cat-back straight pipe

...

 

I'll have it measured next time I'm out and if it's over 100 db, I'll add a glasspack before the L pipe.

 

Just an update - With the L-pipe alone, car was quiet enough that no one even bothered to measure it. It's very noisy inside the car though, as the sound travels down and then echos back up. Here is a video of my run with stock intake, cat, resonator but no muffler:

Muffler Delete

Edit: Had the wrong link before.

 

I would do a resonator with a turn down, if you buy the right one it won't weigh too much more than straight pipe will. If the exhaust exits anywhere underneath the car, a turndown is a must on a rotary due to its fireball tendencies IMO.

 

I'm pretty happy with the current setup and with the car not being my daily driver, I don't mind the noise. I wouldn't daily drive it though and would probably add the resonator and extend the pipe to the end if I had to.

 

The sound level will vary based on the site conditions

If you're out in an open area with no wind or wind blowing the sound away from the meter your readings will be low

If there are buildings etc nearby and/or the wind is blowing the sound toward the meter the readings will be higher

If the cat converter is in place it won't throw flames n00bster

 

There is still some soft backfires with the muffler off but nothing that could be visible... regardless I think turning it down was the right thing to do.

What grinds my gears is that our pad is next to an airport and a few houses around that area complain about the noise of our cars... hmmm guess you should have thought of that when you bought a house next to an active airport.