I am currently in the market for a midpipe. I am curious as to how much of a difference the resonator in a midpipe makes as far as tone, volume, flow, etc. I currently have a bonez(rx7.com) downpipe and plan on going with their midpipe but cant justify the $100 price difference between the resonated vs. not if there is only a marginal difference in sound. For reference I also plan on running a Greddy Ti catback. If anyone has any experience with this setup, let me know what you think. What do most of you guys run? From what I have gathered, majority is straight through, not resonated. Is this right?
To stop some unwanted posts now, I know that running a midpipe can cause spiking, creep, etc. I am also aware of the ECU/fuel upgrades required for these mods and plan on getting them along with the midpipe and exhaust.

 

I had a SR resonated MP then sold it.

The differences on my non-seq engine which is louder at idle then seq:

(1) at idle the MP was about 1.5 DB louder than the RMP 3 ft from the exhaust tip.
Measured with a Radio Shack DB meter.
(2) above 6000rpm the MP ran about .1 to .2 AFR leaner than the RMP.
Measured with a M&S UEGO wideband.

 

heres my setup (not my mods)
Large Street port
Bonez DP
MP
Greddy PE Catback

You cant talk over it at idle.....you gotta yell a little bit.....
and yeah it sounds evil but its a little much.....

If my buddy with his 2004 wrx with full pipes and catback parks next to me while im idling...you wont hear his car.....

its LOUD

 

The cat back makes the most difference.

When I first installed my RMP, my cat back was a HKS turbo catback.
It was a second hand used catback. It sounded fine and was not obnoxious or loud.


It then rusted out and was replaced with a PFS 4" SS catback. This turned my car into a very obnoxious car which I could not stand to drive. Even at idle it was too loud. I sold it immediately and took a $150 loss.

Replaced it with another HKS turbo catback and all is well again. Even after puttind a MP back in.

 

I've got a midpipe with a Borla XR1 resonator, and a PFS catback. Very happy the noise levels. Idle and street driving: good tone, not too loud at all. You can easily carry a conversation. Only gets loud with WOT, and mainly when the 2nd turbo kicks in - but at that point, who cares!

I just hate the exhaust fumes.

 

I have dp, and non resonated mp w/ racing beat dual exhaust. Even at 100mph in 5th at near 4000, I just turn up the radio and the drone disappears in my head at least. I can still talk too. Under WOT or in the second turbo's range, fuggedaboudit, but as someone said: at that point, who cares?

 

i have an SR resonated midpipe i'll let go for $180

 

https://www.rx7club.com/showthread.p...threadid=242372

 

I'm very pleased with the Pettit resonated pipe i put in... it isn't any louder then the high-flo cat it replaced, and the tone isn't hollow-sounding... i've heard the same setup with a regular midpipe, and no thanks.

 

I think what I am going to do is buy the regular midpipe. Throw it on and see what it sounds like. I will run it for a while to let the exhaust break in and see what I think. If I dont like it, I can always pull it off and weld in a resonator.
From what everyone has said though, the resonated pipe is alittle quieter. I am not so much concerned about volume, but of the tone. I can live with a loud exhaust, but if its loud and sounds like crap, then I will have to change it.
From experience, I have driven a VW GTI 1.8T extensively with a full exhaust with no cats and it is not all that bad. A little loud inside the car at certain rpms but nothing unbearable.
I guess its all what your used to.

 

RESONATED MIDPIPE... LOUD
STRAIGHT MIDPIPE... LOUD

cewrx71 is correct... it does matter which cat back you have

if it is your everyday driver... you will experience hearing loss AND carbon monoxide poisoning...

good luck... haha

 

If you do a search on Rx-7 Store Resonated Midpipe you will find someone who did a test with a db meter.

WIth a Racing Beat dual CB and Resonated Midpipe, the db's dropped significantly at idle and cruising around town. I want to say it dropped almost 20 db's. But of course at WOT, you aren't gonna quiet anything down. So, if you want to drop the noise at idle and lower RPM's go with the Rx-7 Store Resonated Midpipe.

 

Keep in mind that a 'resonator' is a straight-through muffler. One of my friends talks about a resonated midpipe like it is some kind of mystical device. It's just a muffler and the bottom line is two mufflers will be quieter than one.

The going rate for resonators from borla or magnaflow in that size is $120ish. Therefore, another 100 for the resonated midpipe isn't a bad deal especially considering that price also includes the install labor.

I recently put together a custom 3.5" exhaust system with a single resonator muffler. After everything was installed on the car I stuck a second resonator on a piece of tubing and slip fitted it onto the catback tip. The difference in volume was astounding. Granted, part of the noise reduction may be due in part to the fact that the length of the exhaust system was increased by adding the second muffler.

 

You're right, I read that thread a while ago. It did drop about 20 db's with both the RB dual and resonated mid. That midpipe on the RX7store is the one they buy from www.vrsexhaust.com - uses a Magnaflow muffler that has a larger muffler volume than Pettit resonater and Borla XR-1. The Pettit resonator is very small and doesn't add a lot of volume. The problem with this is that once you go non-sequential or single, your car will drone like crazy on the highway and carry a lot of extra bass that your ears won't appreciate. It also makes you feel bad when you come home late and you have to make all that extra noise without trying. I am planning on changing midpipes and probably catbacks soon. I will try to get a sound meter from Radio Shack and do the test for each part. It seems that the Racing Beat dual is one of the most effective sound reduction tools available though.

On another note, non-resonated midpipes for those of you who haven't heard cars with them installed are very unpleasant. It takes the extra bass drone out of the exhaust and replaces it with a high pitched scream. I think it keeps things from shaking in nearby houses since it doesn't resonate like rmp's do but it does read a higher db rating because of the higher frequencies it produces.

 

I always like the high pitched exhaust over the lower toned ones. My car isn't a
V8 so why would I want it to sound like that?

My old 83 12A street port with 4ft long headers, one pre-silencer, and a Turbomax muffler sounded like a Jap super bike. Even had a Harley owner tell me it sounded great.

 

So IS the 3" RX7store resonated midpipe more restrictive than a 3" straight through MP??? Why?

 

The RX-7 store resonated midpipe is going to be the same as any other resonated midpipe. It uses a larger volume resonator than other midpipes so it will be quieter, but the internal design of the resonator is still a straight through setup. The Pettit resonator is just a bulbed out section that doesn't add a lot of area and the Borla XR-1 is a little bigger, but not as long. Magnaflow resonators have full sized muffler bodies for more sound control.

As far as resonated vs straight 3" piping, I think there isn't really any noticable difference, but if you were trying to make the car all out on performance, you'd have your downpipe aimed at the ground with an open turn down and that'd be it for exhaust. On full piping setups, resonators might cause a slight loss in exhaust gas pressure at the location of the resonator, but I don't think it would be enough to drop gas velocity enough to see a performance loss on a street car. You really only need to worry about horsepower loss if you're using a muffler that doesn't use a straight through design on your midpipe or catback.

 

That's what I thought, but I had read in the Single turbo forum that RMPswere more restrictive. Maybe it's psychological. The straight through MP is so damn loud that is SOUNDS faster

 

I am assuming that the Rx7store's resonated MP uses a flow through muffler and therefore, no HP loss between that and a standard MP.