My setup is all cheap stuff – all welded up ($300 parts & labor) at my local muffler shop.
Dual header kit - (Mazdatrix w/RB flange)
dual $20 "turbo pack" presilencers
dual $20 glass pack bomb mufflers (stock tips welded on)
- And yes the bombs hold up OK out on the end of the pipes where the exhaust is cooler. It's not too loud cruising at light throttle. It talks to you at WOT.



check out the sound byte in my sig.
(best with headset or sub woofer)

 

A single muffler will not weigh 35lbs, but all the piping and that muffler add up to the 35#. I'm not talking about stock either. I'm talking about good 2.5" aluminized steel tubing.

When you consider that the A/C system weighs roughly 50#, taking another 35 out with the elimination of an exhaust tip is pretty much free weight reduction.

No one has mentioned the change in exhaust gas velocity resultant from the duals and fake duals. Scavenging is greatly reduced if not eliminated with an uncollected exhaust. Even the boinger guys know this and use H or X crosover pipes.

 

Here's a question. Would a true-dual or a collected, dual muffler set up work better for a turbocharged rotary? Sorry, I'm a newbie when it comes to exhaust dynamics...what exactly is scavenging? If you guys have a site or book where you learned the ins and outs of exhaust dynamics on the rotary, I'd appreciate it if you'd send it my way. Thanks for the replies.

 

I was just curious--will a local muffler shop mount a system on a car that doesn't include a cat like that? I mean--what kind of hassle did you get if any from them? I live in Kansas and we have NO emissions testing or inspection laws here. I just wanted to know if they said anything to you about it.

 

No. Turbo cars dotn follow the same rules for exhaust tuning. On a turbo car, you want to maximize the pressure difference before and after the turbo. Big pipe, less restriction after the turbo makes the turbo spool faster and make more power.

 

Dang, I had a moment of idiocy. I don't know how you'd get 'true duals' from the outlet of a turbo. Well is there any advantage to sticking the exhaust out to two big mufflers instead of one, other than noise reduction? I would think it would allow for more flow, but I don't know if the pipe split would cause any negative turbulence. Thanks.

 

i think you can make true duals on TII's if you have Twin turbos right?

 

Yes it is possable to have a downpipe coming off each turbo. I dont think you can do that on stock TT setup, I think you need to have dual external wastegates. But Im not to up on turbos, so I could be mistaken..

 

Why bother converting to twin turbo's? Singles can make the same power, are cheaper, more efficient, simpler and weigh less....

 

well i know i am going to sound like an idiot by why would one turbo be better than two turbos of the same size as the singe?

 

I understand, I was just answering the question he asked about true duals on TT cars..

 

Try and spool two T-78's on a 1.3L.... lol

The point is that you use a single bigger turbo.

Also, I'm no third gen expert so feel free to correct me here, but the sequential twin turbo system on the third gen and cosmo uses the exhaust in series to spool both the turbos of a single collected manifold. Dual exhaust plumbing would eliminate the source of spool from the secondary turbo.

 

well I think if you were to make a custom manifold that separated the exhaust that fed the turbos both would spool up. I get it know though. More exhaust to spool on turbo than half for each twin. thanks for not flameing me.

 

V or Flat (opposed) engines runing dual banks of cylinders would better benefit from a multi turbo set-up. Smaller turbo's spool faster and make boost lower in the revs and those have their place, but with the limited space and exhaust volume of the rotary it is not cost or performance effective to keep or further develop the twin turbo system. A single can simplify the works and produce the limit of power the block will hold as it is.

 

i was always wondering why dont people get one small turbo and one big turbo??? wouldnt the small one spool fast producing more power off the line then when that power decreses the larger one would take over and give it its power???

 

Other way around and you have the sequential twin set-up on the RE/W.

One big one (HT-18) and then a smaller one (T-3) when the bigger one is cashed then the smaller one steps up the rest of the flow. Stock TII's use the single HT-18.

 

That is the idea behind the FD twin turbo system.

On the subject of collected dual exhausts, aftermarket setups like the HKS (I have a Dynomax) weigh about 15 pounds less than the stock dual cat-back. What a nice sound these old school collected duals have when mounted with a header and presilencer. Though you could save 10-15 pounds further by going with a single . . . but it would be much louder.

 

Can we get some more input on this topic. I plan on having a muffler shop make me some cat-back piping, because Im still running the stock Y-pipe. Which would give more power, single or dual? I dont plan on too much road racing, mostly maximum power.

 

i'd defenetly go with true duals if you have the cash. It's pointless having a fake 2nd. It only adds weight and if people find out ur not really running true duals, u might even be called a ricer

 

I noticed a little more bottom end with my 2.5" single having gone from full 2.5" custom duals. But I also changed the location of the first muffler to where the cat was from where the Y pipe began. No top end change in performance with either.

 

Wouldnt a dual setup be quieter than a single. Sorry im just trying to get all of the pros and cons of both before I choose. The dual would have two mufflers so it would be quieter right?

 

A "true dual" wont be any quiter than a collected single. (maybe slightly, but nothin to even worry about). Yes, a collected dual will be queiter than either a full single or true dual, but also yields the least HP. Id take mazdaspeed7's advise, as he had the ture dual setup and obviosly didnt like it. I myself see the collected sigle as the best all around system. Its the Lightest, produces as much HP as true duals, and is cheapest.

 

In a collected exhaust, the exhaust pulses cancel out each other somewhat. So a collected exhaust will actually be quieter than a true dual setup using the same mufflers. Aside from that, the collected exhaust will have a smoother sound, and seem quieter than it really is.

 

The N1 was inspired by the N1 Endurance cars ie; Skyline, RX7,Supra, created for cars needing one of the best free flowing exhausts....and the N1 sounds totally different from other ones..i think most of the other exhausts sound kinda raspy.

 

So a collected dual is the quietest, and the collected single yields the most power?