Benjamin4456

Parts arrived late last night . I got them unpacked this morning:











Nice 'n shiny . They also pass the 'tap/flick' test with flying colors (no resonance, just a dull thud).

Additionally I did some internal investigations and discovered that these mufflers are in fact a straight-thru. Look, you can see the inlet pipe from the exhaust tips.



The folks over at RB also told me that these mufflers have been being tweaked for a while and now they are finally finalized (this design has been around since what, 2017?). I might have misinterpreted it but to me it sounds like up until now they were still working out some kinks/making improvements; not certain on that, but that's how it sounds. Here's a quick quote for what I'm referencing: "We’ve made some minor changes to the final versions, I now have the required components to produce larger batches in shorter time periods. The 83-85 mufflers are actually being welded as I type this ..." I was also told their supplier in Italy was sold and the new owners were not keeping up the quality in terms of communication, products, or shipping and that's a main part of why they moved back to in-house production.



I also found that after the dual perforated cores there is a restriction that necks down to only about 1-1\16" for a short distance which seems a little odd (focused on in the above photo). Perhaps it's for noise control but it does seems awfully narrow. I hope this setup won't be too loud, certainly hoping for no louder than my blown out exhaust is. Unfortunately I'm going to have to do a little more modification to the inlet pipe than originally figured. The 60mm pipe necks down to whatever the stock midpipe size is right before the flange, and of course this is far too small for my 2.5" system to mate to. It looks like I'll have to cut off enough to get to the 60mm pipe section and then add a new short 2.5" piece for the new flange. Not exactly enthused to cut up a $300+ part, but oh well, it's going to have to be done.

Pretty soon here I'll get the flanges ordered and then once those arrive it'll be time to start mocking up the exhaust - probably within a couple weeks.

yeti

iTrader: (1)

I had to cut my flange off too. The car still sounds loud on the inside (I think that's my intake though) but it's actually fairly quiet behind it. I was finally able to drive behind it the other day to hear it. I didn't get the opportunity to ride beside it or anything like that though.. :/

j9fd3s

iTrader: (3)

noise is a wave, and in the case of the Rotary the noise is the difference between the positive pressure wave and the negative pressure wave. there are a few ways to reduce the noise, one way is to put a restriction way at the end of the system, and this makes the waves run into each other and at some point they just become a steady flow, which is quiet. if you size it correctly it doesn't impact flow very much and power is basically unchanged.

the other way is absorption, perforated pipe wrapped with insulation, and then you can have some chamber/baffles so that the waves cancel each other. the rotaries pulses are so strong baffles live a short life

Benjamin4456

Well I'm impressed. Based on what I've been hearing from folks lately about the new RB system sounding terrible, I didn't have high hopes. I was wrong.

The system is far quieter than my old setup, both being straight-thru designs. Idle is quite tame, 2k fast idle won't frustrate neighbors anymore, and when I get on it it's still plenty noisy. A bit over a mile away - through houses, lots of trees, and down a twisting hill - a friend of mine could hear me when I floored it from a light. However, when driving around town conversations are easy, and I can leave a stop light with normal acceleration and it doesn't sound like I'm trying to race someone unlike my old exhaust.

All in all very pleased with the setup, it might even be a little quiet for my taste but I think I'll appreciate that over time. I'd certainly call it on the quiet side as far as aftermarket exhausts go (in general, for all cars). A great exhaust, in my opinion, for a daily - cruising on the highway it's almost inaudible with the windows down.


So that's enough of me reviewing things, here's a detailed list of the setup:
- RB collected header (non "street port")
- RB thick wall mild steel 2.5" piping
- custom laser cut flanges (figured out it was cheaper than buying them premade)
- Vibrant 2.5" dual bolt flange gaskets
- RB 2.5" Universal Presilencer
- RB 83-85 Power Pulse Muffler
- swappable Magnaflow cat (99006HM)
- Rustoleum black grill paint for mild steel parts (works great on exhausts)
- M12 grade 8.8 bolts on all flanges

To get everything to fit was a bit of a chore, particularly the presilencer (it's pretty big). The muffler fit exactly like my old muffler which came from my FB, so in other words all the mounting points were slightly off for my SA. That was fixed pretty easily with some short bolt-on extensions to span the gap. Other than that the muffler fit fine - the mounts are probably designed for the FB chassis. The presilencer only has perhaps four inches of ground clearance, although I think I can push everything up just a hair. Haven't collided with any speed bump yet though, so I think it'll be ok until I go with a new suspension setup. Fitting the presilencer up front might be a little easier, although because I needed that spot for a cat it was not an option. Rather it's about two inches ahead of the muffler flange.

Unfortunately my audio recordings didn't come out so well, so I'll try to get some better ones later. For the meantime though I do have some photos.



















Perhaps part of why I am not experiencing the 'ricey' sound people are describing from RB's new muffler is that massive presilencer. Otherwise maybe they made some improvements on this latest batch (of 83-85 mufflers that is). Can't really say unfortunately, although if it continues to sound how it does now, I'll be content. I also measured the piping on the muffler and it appears to be 16 gauge stainless, just for reference.

Thanks to everyone who convinced me to go with the RB muffler. I have a feeling that my originally planned Magnaflow would have been, oh you know, just a bit louder... It's funny too, my car almost feels faster now, even though the exhaust restriction hasn't changed much between the two systems. I think it's because the car is quieter, and so more throttle doesn't sound like it's trying as hard as before. I wouldn't say it's quicker when wide open, but it sure feels more responsive around town.

Rx7fb spirit r

Your exhaust will be to quiet then. 🤔

Benjamin4456

Haha, well not quite. My phone has been having some issues recording audio lately. For some reason it suppresses the volume much more than it should, so the only time you can hear anything is right at the beginning of the clip before it nerfs the levels - it happens with both video and plain audio recording as I discovered last night. Hopefully I can get that sorted out and get some audio up for y'all.

Benjamin4456

Seems I forgot about getting some audio up for you folks. I still don't have any clips from outside the car or while idling, but I do have this short video from my road trip a couple weeks ago. My phone is still having trouble with audio, so you'll notice that about halfway through the clip sound cuts out. The clip is mostly just cruising in some twisty bits, but around 1:16 on the timestamp I get a short 3rd gear wot pull (I believe I topped out around 5.5-6k).

The setup in the clip is as follows:
- S2 12A with a "medium-small" extended port on both the intake and exhaust
- Hogged Nikki; re-timed mech secondaries, 24mm/30mm venturis, trimmed everything, etc.
- RB collected header
- RB universal presilencer
- RB 83-85 Power Pulse muffler
- no cat currently installed

Here's the clip: https://photos.app.goo.gl/SgUuBk7Z3zdU8P5n8

Some of the deeper frequencies weren't picked up so well, but I think it should get the general idea across. In the clip it sometimes sounds a little buzzy, although in person you don't hear that all all. And yeah, there's a fair amount of exhaust burbling going on (quietly for the most part) in case anyone was wondering what those subtle popping sounds are. Oh, and the drivers window and sunroof were both open.

Maxwedge

iTrader: (1)

Is that your 7 or a Prius? So, so, quiet.

Benjamin4456

Like I said, I'm glad it's a little louder than it was when I first installed it, because yeah, it's pretty quiet. In some ways though it's nice. I don't have to bother people or myself just driving around, but when I get on it's still plenty loud.

I should note though that the recording is a little quiet. I turned my speakers up a decent amount (compared to normal) and then it sounds more true to life. For those who watch it I'd suggest doing the same, otherwise it really is almost inaudible.

Maxwedge

iTrader: (1)

Oh I could hear every car and truck that passed you, but your car sounds stock. I'm jealous. 3 of my 4 cars are too loud and I regret it. I must be getting old.

Benjamin4456

Well it's been a few months with this new exhaust and I figured I'd share some thoughts on it now that it's broken in.

First of all, it's much louder than when I originally installed it. It's not bad loud, it's just a significant change. Originally you could barely hear it at idle and at speed it was more "whoosh" than anything else, now it's perfect in my opinion (except for cold start sustained idle speeds, in which case it's a little loud for the early morning). Compared to my old setup, the volume is perhaps a little less around town, but when you get on it there's no way you're not being heard. Bonus for this setup over the previous is that there is zero drone, none. Cruising in third and above I easily hear road noise and my transmission over the exhaust. I'd say that if my car didn't require a five minute warm-up on cold starts, this would be the perfect daily exhaust. Even so, it's really not too bad and in my opinion the tone and lack of drone makes up for it.

So far I only have one decent recording of it (phone is still having some issues), but I'll attach it below. You'll notice that until the 21 second mark or so there is very little low end. No clue why, but right around that time stamp my mic figures itself out and actually starts getting a fairly accurate recording. At the file name suggests, my phone was sitting on the roof of the car. Also since the hood was open there's a bit more air and ticking sounds than you'd normally hear (still working on solving the ticking sound). Max rpm reached in the recording is 3k at maybe 1/4 throttle during the blip. You can also pretty clearly hear the carburetor if anyone was wondering what that was (modded Nikki goodness ).

Anyway, I'll try to get some better recordings eventually, although who knows when I'll remember and have a chance. I'll say for anyone who may be considering a similar setup, it's going to be really quiet when you first install everything, just be aware. Over time it will get louder and a bit fuller in tone, but at least in my experience (aka, so far) it never gets raspy or sounds like a Honda, not even close. I am going to bet however that the large universal RB Presilencer is doing a lot for the tone and keeping the raspiness level down, so keep that in mind.

Now finally here's the short clip (remember, the mic is a little weird until ~21s).

yeti

iTrader: (1)

After reading @Benjamin4456 's review update, I wanted to leave an update on my experience. My "loudness" issues were definitely from the intake, which I have more or less fixed (Weber tuning, had a eureka moment). We share more or less the same exhaust setup and I second his results.

diabolical1

iTrader: (3)

.
my system is whatever they sold between 2004-2006, but it was the same experience. i only just saw this thread, but i'm glad you settled on the setup you did. it's true that people may make better headers now, but in terms of exhaust systems, i still maintain that, for our cars, RB is the best in most of the metrics that matter.

i'm glad to see you continue to make progress with your car. i really dig your work and the results.

as far as i am concerned, you would be correct. many years ago, my brother had one of the original RB systems on his '83 GSL. at some point he sold that car and got another '83 GSL, but this time he put a system together an RB header and muffler with some leftover (still in the box) Rotary Engineering parts i had laying around, and the tone was totally different. i admit it's a tad throatier (and louder) with the RE parts, but basically, the presilencers made the difference.