GoRideSno

RMB adds 10 HP?
From 928 Intl site I see that an RMB adds 10HP "Polished stainless steel adds 10 HP and a muscle car sound" I have no reason to doubt this especially given that it is stated by I assume Mark Anderson.

However someone says that it dosen't add any power and that the 27lb rear muffler of the S4 is basically just a straight pipe. I find this hard to believe. Why would Porsche put something that is 27lbs on a car that is equavalient to a straight pipe?

I am afraid that with the X pipe my car will be too loud, but 10hp is 10hp.
Does the RMB add 10HP?

Andy K

sweanders

Since you seem to have access to a local drag strip and it takes very short time to swap the RMB on/off the car maybe you can try with and without it there?

GoRideSno

Sweanders,
Actually I live 100 miles from the nearest 1/4 mile track.
Andy K

heinrich

That someone is wrong.

The RMB in concert with other mods will make power. In other words, if by the time the exhaust gases get to the rear muffler/RMB, they are already slow, then the RMB will have no effect.

I have tested an Ott X with and without the RMB and the RMB allows 100% free flow, whereas the rear muffler in this scenario creates back pressure.

heinrich

Andy Anders is quite correct. With your car, your driveway, the local Safeway, and any freeway onramp is a "nearest quarter-mile track"

pewter82

I have the RMB on my 91GT and it sounds great and I was told it was a 8-10 hp gain, but that is probably not noticable on track numbers or even the seat of your pants.

jason

91GT India Red/Tan GTS rear RMB 56k

bcdavis

The dyno is the only way to tell.

And x pipe is already a straight-through setup.
Add an RMB, and you pretty much have no mufflers.

That is going to be ludicrously loud.

Just get a muffler that advertises zero restriction.
There are several high-flow mufflers out there, that claim to have no backpressure...

heinrich

BC, your car would be Pat Edwards loud with no cats and no rear muffler. But my '87 has the GTS-size large centre mufflers, and my RMB/Ott-X combo have served me very well for about 3.5 years, and it's not ridiculously loud. TomM had the later smaller mids with the same setup, and that was ridiculously loud. However, the older cars with larger valves and overlap, are Pat Edwards loud. I mean, so loud that you can hear the car idling a quarter-mile away.
Heinrich

Gretch

The RMB on my 89GT makes just enough noise so my neighbors can hear me entering the underground garage. They know It is me, even the ones on the 7th floor of the building. If I remove anything else, I will be crossing the line.

bcdavis

But you still have your mid-mufflers, right? And your cats?

Jim_H

Andy,

The X Pipe with a stock muffler will definetly add power, it will not be too loud. The X Pipe with RMB will Be too loud.
I have a stock GT w/ X Pipe and stock rear muffler that dyno'd at 301 at our last Dyno Day. This on a day when most wanted higher #'s so I think the results were fair.

If most GT's dyno at 280 or so then the X Pipe was probably worth 20 horses or so on the Red GT.



Also, no cats.

Drewster67

I thought I would share some photos of my new exhaust. Rather than going with a magnaflow muffler, I went with a flowmaster 40 series 3" in and 3" out muffler.

I ran the stock exhaust - 2 - 2 1/4" pipes into the single 3" pipe into the flowmaster.

I am quite pleased with the end result. More power and a deep throaty muscle car sound - AWESOME Man ....I tell ya - simply awesome.

The work was done at Scottsdale Muffler in Phoenix for 175.00 greenbacks.
The best money spent this summer.

MSDS headers - dual cats and a single 40 series muffler. TTTThhhhaaattts all Follks!.


Enjoy.

Gretch

nope, no mid mufflers. 89GT only had one muffler. there are two small resonators and two cats. The resonators are in the same location the "mid mufflers" were in other year cars.

With this set up on the 89GT the cats ARE the mufflers.......

Drewster67

Heres the bathtub I removed along with the resonator.


FYI

bcdavis

I'm pretty happy with my Flowmaster as well...