Im trying to replace my current muffler with a quieter one.
I want to get an RB dual but feel the price is too high . I already have the piping and basically need to just weld in a new muffler, Im figuring a muffler with the same sizes or close to the RB would sound almost the same. After all it's not like a single inlet dual outlet straight through muffler can be that different from any other just like it in design.

It looks to me like Magnaflow has a few that may fit the bill.
CAN SOMEONE PLEASE JUST TAKE A FEW MEASUREMENS

a tape measure will do just fine

what I want is cannister size, oval length and width as well as over all length.

then I would also like the dual outled diameter. I know the tips are 3" but I don't think the pipes exiting the muffler are it looks to me like they are more like 2.25-2.5"

if you run the numbers a 3" pipe is nearly 7" cross section area
and two 2.25" pipes have nearly 8" cross section area.

it's mostly that outer pipe diameter that I can't figure out.

also magnaflow has some pretty nice 3" tips with 2.25 inlet diameter.
if this works the whole thing in polished SST will only cost about 200$ and should sound the same as the overpriced RB dual with the same stock look.

 

That's a really bad assumption. A large factor of the sound/noise output is determined by the internal construction of the muffler, not just the external size of the cannister and the inlet/outlet size. The perf-pattern, %open area, amount of absorbing material, exact shape of air passages, etc, will have a large effect on the noise levels/sound quality.

That said, I would measure mine for you but my car's in the body shop right now... Good luck with your project.

 

My RB dual tip is ~ five years old, so I can't say whether it's the same size as the current ones.
Quick measurements yield
length 17 3/8
width 10 1/2
height 6 3/4
the center of the outlets is 4 1/4 down from the top of the back.

About the outlet diameter - I was miffed about this when I got it, and still doubt it's optimal. The id of the outlets is 1 7/8 (measurement taken by inserting 15/16 Craftsman open end wrench a few inches where the outlet ID shrinks - the wrench measures just less than 1 7/8 and slips in not quite tight).
That yields
3" inlet = 7.07 sq inch area
2 x 1 7/8 outlet = 5.22 sq inch area.
So, the outlet area is only 78% of the inlet area. Must be restrictive, and who knows how the transition from 1 to 2 is made internally, and the laminar flow characteristics of two pipes are vs one. These things are popular, but I can't figure that they're that efficient.

That said, I agree with Rynberg that the internal construction makes all the difference. Flowmaster would be my preference, if they have anything close.

And please post your results if you complete the project - catbacks are ridiculously expensive.

Jonas

 

Those outlet sizes seem quite a bit smaller than mine (last year model, not the older RS-R style exhausts). On mine, the single inlet goes into a smooth Y, ie, there are two separate paths through the muffler.

In defense of the RB, it's construction quality (and looks) are very, very good. Very good welds, good quality materials and construction.

 

Rynberg, they certainly could have changed over the years. When you get your car back from the shop, perhaps you can check the ID, not right at the back, but 2 or 3 inches into the tips - mine reduce in diameter there.
Or anyone else with a recent RB dual ...

Jonas

 

that's great information!

there are several cannisters out there that run pretty close to the same size. the only dimention Im not able to replicate is the offset to the outlet pipes.
all the universal mufflers seem to keep it in the center.
also very ingenious way to measure the outlet pipes.
i suspected from the pictures that they wer a bit smaller but never thought they were that small.
any chance you can put a flashlight in the outlet and determine if the internal Y is at the front or rear of the muffler? Im trying to see if it splits immediatly after coming in or just before exiting.

I agree. but if I can get close, ill take it.

Ill look into that another member on the board just put a 3" inlet dual 3" outlet on his car and said it desn'e droan... but it does get loud when he steps on it.

now that it's winter im not so bothered by the loud noise....windows up.

 

be careful building your own exhaust. very few mufflers can stand up to the heat of a rotary. the reason the rb catbacks are so good is they dont tend to burn out like most any other mufller you would purchase including the flowmaster. it even states in the flowmaster literature not to be used on a rotary. the shop i work at contacted flowmaster to build us a muffler for our rotary powered racecars and they flat out told us no, never no how. dont get me wrong i use flowmasters on my v8 and am very happy with them but have been able to burn out every muffler ive tried on my ported first gen inluding flowmaster, edelbrock and dynomax. i have a rb duel on one fd and a stock catback on the other. no failure issues but your right the price is very high for the rb catback. at least the duel looks almost stock, a must in cali.

 

Because you asked...

The new style RB dual had 2 3/8" ID outlets.

 

Om ordering the magnaflow 14588 today.
looks like the cannister measurements are nearly identical.
the only thing not the same, the outlets are 2.5" not 2.375 and they are not offset towards teh bottom like the RB.

now I have to find some nice tips.

 

OK found some tips they are magnaflow 35102
the strange thing is they don't slip over the outlets of the muffler so Ill either have to expand them or weld them on.
Im thinking weld them on since the muffler is going to sit in there at an angle and then I can have the tips exit straight.

total cost so far was 148+ shipping from a near by town. if I get it tomorrow Ill take a few pictures and some sound files them install it and let you all know.

 

ALL DONE.... well I installed the muffler this past week and cut the 18" tips down to about 6.5". the results were great...

nice and quiet deep tone at idle and cruise. but when I step on it it open right up gets loud but keeps that deep tone. no more raspy can sound!!! all in all teh actual sound level has only gone down a but under load. it's the Tone that has changed. now it's great.
I recorded before and after movies with my digital camera. if anyone can show me how to post them, Ill post a link to them here.
if you email me

gregory.denne@framatome-anp.com

ill just send you the files before and after.
As you would immagine the dual 3" tip looks very nice too.
I cut off my old cat back muffler and needed to remove about another 3-4" of pipe to make room for this one. then I just tig welded all the rest of it up and made some hangers too.
Total cost 150$ took me about 6 hrs to do the whole job. Lots of tack and fit to make it all just right.

 

someone host plz id really like to hear teh exhaust tone