Patman07

Which one makes morepower with the RB header and presilencer.

Cost and sound are not an issue, talking strictly power gains.

fcdrifter13

Borla

rx7 FC TII

iTrader: (3)

RB true dual exhaust....loud and make your ears bleed but gives alot of power

Patman07

Anybody have any dyno charts? When you say True Dual RB Exhaust thats all the RB is right?

BklynRX7

Its not that bad. It just a deeper tone than collected exhausts.

sik7ven

if u dont have the proper mufflers like me, its pretty loud, i bought my true dual setup used except the headers were brand new and i didnt get the mufflers. I had to be stupid and drive my car open y pipe and of course, ridiculously loud. I put my mufflers on to realize i had them blown. I replaced one of them so i have one blown out muffler and one ok muffler. In my situation its loud as hell when i hit about 35k, I still recommend it, true dual set up is the way to go on an NA, just get good mufflers

BklynRX7

Oh ok, I thought you were talking about the complete rb setup.

fcdrifter13

I think he is just talking about the y pipe back no true duals. I am a fan of the RBs sound but have you ever seen one cut open?

wthdidusay82

iTrader: (15)

I got the borla catback over here and I think its a great exhaust , but alone it really doesnt bring out as much hp as it will with a header and straight pipe.

I at first just had the borla catback on the car and thats it, it made a slight difference. Smoother powerband, better sound, more throttle response.

After installing headers and straight pipe the exhaust basically got a deeper and louder sound to it and you could definitely tell a difference in power.

Borla Catback adds + 8hp + 10 Tq (these numbers with 15% drivetrain loss give 6.8 hp at the wheels and 8.5 torque to the wheels) I dont remember where I got these numbers from I just remember from when I bought the exhaust.

Racing Beat claims dyno results yeild 5-7hp more than stock (wheel hp)

Racingbeat headers will add about another 11-15 wheel hp

Having a straight pipe will add 1-5 wheel hp (im guessing)

So either way racing beat or borla, theyre both the same exact size piping and pretty much the same exhaust and will both yield pretty much the same results even going by what they give for there estimates. (the only exception being racing beat's true dual system)

So if you buy the racing beat youre paying more for the name than you are for better hp potential , imo.

adrock3217

You are wrong. You are a moron.

The Racing Beat true dual exhaust is only slightly louder than the collected version, and you loose the high-RPM fart-can sound the collected makes.

Don't speak if you don't know.

adrock3217

Actually, the straight pipe (assuming you have an alternate way to control the auxiliary ports) will give a MUCH bigger gain than the headers. The catalytic converter, in all rotaries, is the biggest hindrance on performance.

Oh and, aside from the name, the extra price for the Racing Beat is that is doesn't sound like crap. It's a got a classy look, classy tone, and is something you can roll up to a business with, and not look retarded.

7dust

iTrader: (14)

Its LOSE, not loose.

Moron.

MrFC3S

come on now guys... so much anger...

so leme get this strait... Headers+No Cats+Strait pipe is the best recipe for Max HP? I dont care about how loud it is. Aslong as I get no tickets.

also, the car in question is an S5, any worries about the AUX ports not working properly?

Sgt. Pepper

If you're worried about noise you will be just fine with a full Racing Beat exhaust. Header, pre-silencer, and catback. It's pretty quite at idle and bellow 3K RPM, but when you get on it it gets a bit louder, but sounds real nice.
I would choose Racing Beat over Borla just because I like the look of the RB mufflers and they do specialize in Mazda Rotarys.
In fact I will have 2 sound clips up online soon that I just recently took of this setup. I'll post it in this thread if I remember.

Have you ever heard the true duels before?

I want to see the picture of the RB muffler cut open again though, I can't find it. Saw it a while ago and I was amazed because they call their mufflers "straight through" **** looked like a maze in there.

Ahhrevenge

iTrader: (7)

So has anyone answered his question?
What's the best way to achieve hp gains with an n/a?

Roen

iTrader: (2)

I just want a S4 GXL with an S5 wiring swap, RB's Headers, Borla's Cat and RB's Mufflers.

You won't even know it's on.

rotarygod

iTrader: (1)

There is no one correct answer for "what is best" or "what gives the most". Each option should always have a disclaimer that says "it depends". A true dual may be quite nice on a stock or mildy ported engine but put them on a bridge or peripheral port and suddenly the story is very different and it becomes the worst exhaust option. There are many factors that affect exhaust design and everything is a compromise that works best in one place but not in others. A true dual is not always more powerful. A collected system is not always more powerful. However each system depending on application could be but they won't excel at the same things in the same place.

There are a couple of generalizations about rotary exhaust that always apply though and it comes down to noise and tone. The farther back a rotary exhaust is collected (a true dual is collected at infinity which is pretty far back!), the harder it becomes to muffle. You give the exhaust pulses less time to mix and have sound wave interference. Of course there is far more to this wave interaction that just noise but I've been detailed about that in the past and won't do so again here. The closer to the engine you collect the exhaust, right at the engine in the case of a stock n/a RX-7, the easier it is to quiet it. The pulses have far more time to for acoustic cancellation.

The farther back a rotary exhaust is collected, the more you hear the individual pulses. On a true dual system, when you stand between them it is like having an exhaust in stereo and it is quite easy to hear the individual pulses. The farther forward the exhaust is collected, the less this is apparent and the smoother the sound is. It is for this reason that explains why a true dual exhaust sounds something like a cross between a Harley and a poorly running lawnmower. It's functional sounding. Not beautiful. There is still more to sound than that though.

The farther back a rotary exhaust is collected, the deeper the exhaust tone (sort of). This has to due with the fact that a long single pipe is basically an organ pipe and actually it is the principle of organ pipe resonance that is affecting tuning on such systems. I longer pipe will highlight the lower frequencies in the system and help quiet the higher tones. This is why you don't notice the higher pitched "fart can" sounds as much. It doesn't get up that high in frequency. When I had changed over to a dual system on an older car that I once had, I couldn't tell when to shift based on sound anymore. At 8000 rpm the engine sounded like it was at 4000. The "lower" tone isn't a sound like a big tough V8 growl so don't expect to gain a tough sound from it. It just sounds like you are at a lower rpm.

The closer to the engine the exhaust is collected the higher the exhaust note. As was just pointed out, we effectively have changed our organ pipe length. Now we have a couple of them. The shorter primary pipe length doesn't give longer lower wavelengths time to gain strength but does favor higher pitched notes. The tailpipe which is anything after the collector, has a small secondary effect on all of this as well.

On my old car, the best sound I ever had was from a simple header to a 2-1/2" straight pipe in place of the cat, to the y-pipe and through 2 Brullen straight through mufflers. It was very loud but sounded very smooth and alot like a sport bike. I cut the header collector off and made it a dual running through the same mufflers and suddenly it got even louder and the tone changed to that of the cross between the Harley and a poorly running lawnmower. It went from sounding race car to sounding redneck. I didn't like it but there was a change in powerband. Low end power improved and mileage increased but ultimate top end power fell off. One system was better than the other in different places but neither was better than the other everywhere. For street use the dual was nicer but the collected sounded heavenly. That had a lot to do with the mufflers though which takes me to the next point.

Mufflers. Don't be tempted to think that just because Muffler A can outflow Muffler B that Muffler A must make more power. Maybe not. If each muffler can flow at least as much or more than the engine can, they are both functionally equal. You need it to flow as much as you need and no more. More won't help. Lots of people have a hard time grasping this simple concept. A good quiet muffler that is fairly cheap and flows well is the Dynomax superturbo. No it isn't shiny chrome. No it isn't stainless steel packed. No it isn't a straight through design. None of that matters. It flows what the engine needs and that is all that matters in terms of making power. The fiberglass burning up is not an issue as that is primarily an issue when they are used a presilencers much closer to the engine. Mufflers that don't survive as mains on the rear of the car are just porry built. Edlebrock mufflers are a great example. They are stainless and they disintegrate.

Generally speaking a larger muffler is better. Not necessarily larger in terms of core area but rather total area. A small 6" round muffler is always going to be loud if it is a straight through design. The same core area however in an oval muffler that is larger will be a little quieter but also have a deeper tone. The small mufflers are typically what give an engine it's raspy character. Other factors play a role too but in the end it is usually the crap mufflers on the market that are responsible.

I know after all of this you are probably wondering what the best setup is for your application. I can't answer that. No one can regardless of what they try to claim. There are different ways to approach it and different manufacturers to choose from. As long as both of your muffler choices flow what the engine needs, and they each probably do, there should be little if any power difference between them. It really comes down to tone and price at that point and asking which sounds nicer is always going to be an opinion.