You could have just made a new thread asking the question, and the Racing Beat header collects into 2.5"...dunno what kind you got a hold of. Anyways, the ideal exhaust for naturally aspirated rotaries (or at least what EP guys use) is a system that is true dual up until the system collects after the axle and at the final muffler. Supposedly it provides the best balance between being lightweight and having a useable powerband.

 

i might go corksport single when i put my turbo on, dunno yet i'm kinda partial to the dual exhaust but, weight is always a factor

 

As nice as RB? no. I've yet to see any single be THAT nice.

 

Well, now that I know that the RB header collects at 2.5" (i don't know where, but I read that it only was 2"), I'm thinking that I'm going to take the GReddy power extreme cat-back system I have now and just use one of the mufflers on the end of a 3" pipe, and run a series of increasing diameter pipes that get me to 3" from the header back in a single exhaust setup. Probably mount it solid to the chassis, too, just for stability and security (don't want the rubber doughnuts to fall apart at the track now do I?).

 

youre talking about rice and youre getting N1's? :

 

We sell our muffler section separate from our exhaust system. It's a straight through design similar to the N1. More a resonator than a muffler though... If you don't like it loud, I might look elsewhere if I were you.

 

Here is what's on our FC EProd car. RB header, seperate back to roughly passed the axle, it makes a turn toward the drivers side first. Collects to 3" and turns toward the rear, left side bumper cut out. Through a SpinTec muffler (3" in, 3"out). We don't care about anything below 4K rpm. At 9500 rpm it measured 93db at the last event. We did some testing and found the SpinTec is giving us a lot of backpressure, over 15Hg (H20) at 6000 rpm, thats how high the gauge goes so who knows what it is at 9500 rpm. We can be 103db so we are testing mufflers for less backpressure which will most likely be louder.

 

I hear Dynomax bullets flow insanely well. They cost about $35 apiece, and come in a variety of sizes and diameters. Also look into Borla XR-1s if you have the dough.

 

On those Dymomax bullets, I looked at them and was worried about the stuff they are packed with. "Continuous roving" says "fiberglass" to me and I know it will burn out fairly quickly and get REALLY loud. I did like how I could just about stick my arm through them, still might try one.

 

My n/a setup is a pacesetter header which collects to 3" and I have that going to a ebay 3" presilencer to a 3" corksport catback. It is ungodly loud, but not as bad as running open header. The silencer for the muffler has been JB welded as far in as it will go so help silence and create some good back pressure with its 1" outlet. With the ports shut it gets almost 300 mpg a tank and makes decent power. The the ports wired open It gets 250 and has crazy top end power. I can't chirp the tires anymore, but if you take it to 7500 the car will leap forward so hard. Personally I love the full 3" setup on my n/a.

 

Just get new rubber hangers. Mazda put a lot of effort into hanging the exhaust and it works quite well. If you have rubber motor mounts and hard mount the exhaust you will break the exhaust or the hangers eventually.

Most people in the know like Borla stainless for a presilencer/muffler. If the Walker race bullets are packed with stainless they should work well too. Just make sure any packed muffler uses stainless material otherwise it won't last long.

Ok, just looked at Dynomax mufflers. Looks like they are all packed with fiberglass.

 

i got a 2.5 to a resonator to 3 out to a invidia n1 muffler it has a mustang like grunt but itis loud probably gonnago get another resonator installed what do u guys think oh and the fireballs oh my! my bumper is well done

 

If I'm reading this right your header collects on the passenger side and turns toward the drivers side under the hatch area. Magnaflow makes an oval stainless 5" x 11" muffler that is 30" long that would fit under their pretty good. 3" straight thru design ofcourse. I've heard the 6" round version of this muffler on a rotary lotus 7 and it was one of the best sounding ones I've ever heard. The key was obviously the volume of that long muffler.

http://www.justmagnaflow.com/Univers...1Stainless.htm

 

The tip is 4.6" in diameter which will catch some attention ill let you know how it goes [/QUOTE]

 

This week I made a muffler for the EP car. We gathered up all the different mufflers we could get by asking who had what laying around. One muffler was purchased from a stock car supplier locally. After looking at what we had collected we decided to throw the straight through stock car muffler on. It was 3" in and out and about 22" long. There was nothing inside it to quiet anything just a perferated pipe with a bigger pipe surrounding it. We started the car and were able to drive a couple piston engine guys out of the shop because it was LOUD (we knew it would be, they didn't think it would be THAT loud!) One thing we were able to check was the amount of backpressure. It was almost nothing, compared to the Spin-tec we had removed that pegged the guage (16inhg) at 6K rpm. So I cut the outside pipe off of the perferated pipe and made a new larger outside 'pipe'. I stuffed the now 6" dia pipe with lava rock and welded it all together.
The car is definitely quieter and has almost no backpressure. The muffler weighs only three pounds more than the spin-tec, 16 lbs compared to 13lbs. The next test will be if it is quiet enough on the track at Daytona next weekend. I'll report that later.
So for about $50 bucks, new muffler that will must definitely give us more power.