911dev

Maybe as evidenced by a dyno. However, the dyno runs were not run at partial throttle. No way of ensuring an accurate application of throttle between runs.

Not saying I'm right, just conveying what a competent tech. told me. Certainly seems plausible.

Max. torque and range would be the same with valves on or off, I believe, no? Partial throttle with varying load, valves open/closed would alter mid torque, I would think.

I could be over thinking.

Jimmy-D

Sport Muffler Set 991 GT3 "Brombacher" Edition without valves
BES 991 040 60S





$2,195

+ 11 Hp & + 10 Tq Gain.
- 2 3/4" Tubing (70mm).
- 11 lb. weight savings over OEM side mufflers.
- T 316 stainless steel for improved durability over T 304.
- Absolutely NO DRONE in the cabin.
- Does NOT interfere with emissions and will NOT trigger the check engine light.
- Replaces OEM side mufflers and connects to OEM header and catalytic flange.
Our 991 GT3 Side Muffler replacements are vastly different than the baffle plated mufflers stuffed with packing that are common in the aftermarket. Ours are uniquely made with double perforated sound absorption tubes. The acoustic silencer absorption tubes are made in a trapezoidal pattern and are perforated with varying diameters, which isolate and dampen the unwanted frequencies that create drone. These perforated tubes present much less flow restriction than baffle plates at higher gas velocities, and consequently translates into larger horsepower gains at higher RPMs. The resulting sound exhibited is an aggressive, linear, firing-order dominated flat 6 Porsche® sound, which is the closest to a Cup Car in nature. This sound is not a coincidence as our entire “Brombacher” line of exhausts is manufactured by M&M Exhaust, GmbH in Germany who is no stranger to Porsche® racing exhausts. They are tested comprehensively for flow characteristics, flow rate, thermal stress, cracking, and longevity. If you are looking for the perfect street muffler that can handle abuse at the track, look no further.

Only in combination with BES 991 050 60S

Without valve control

LAGinz

I agree that dyno looks odd, but at least they published a dyno comparison with stock. Other than the Akra one, which needs clarification , has any other exhaust mfg. done that? Are you guys really going to spend money when you're not even sure if you're going to lose power? I've gotta admit, I'm puzzled by all this.

LAGinz

Oops---wrong quote, but you get the point

Jimmy-D

I think with these new side mufflers combined with the SW exhaust - this could be an interesting out come. You really are not doing any thing funky here. You may actually be improving things over the OEM set-up.

Very interested in how this will sound/function

ipse dixit

Agreed x2

And Jimmy knows I'm a big MM fan.

vf430

whats everyone's opinion of BBI side muffler bypass pipes? Sharkwerks is center muffler bypass. I heard a BBi car and was impressed. But dont quite understand how its louder with the center muffler intact. Can someone explain the pros and cons between these 2 systems. BBi you lose the valves.

SunnySD

This one from cargraphic looks and sounds pretty good. Maybe a group buy to get the cost down

Money2536

That competent tech is just guessing. I confirmed it. This is the dyno where we did a run with PSE OFF the ON at approximately 50% throttle.

NateOZ

Yep - also has the advantage of being tested as a system compared to putting one together yourself.

Money2536

I agree. My concern about the Cargraphic is that I'll end up in the same annoying position as the stock exhaust with the valves opening and closing. I'm still interested in this if my FVD experiment doesn't work. $5,000 is a lot bigger gamble than the FVD option since I already have the Sharkwerks bypass.

911dev

A few dyno runs attempting to replicate partial throttle don't prove a theory. End of the day, you have your theory, I have mine. It's good either way. Cheers.

Money2536

Closed Valves = Less Exhaust Flow which = Less Power and Torque.
Open Valves = More Exhaust Flow which = More Power and Torque.

I have proven this. This is not a theory. Your tech doesn't know what he is talking about.

Why in the world would more back pressure allow for more torque at any RPM?

NYC_AREA_GT3

Money - keep the FVD side mufflers + SW center muffler bypass pipe installed for the smokies weekend. Can't wait to hear the combo in person.

Just to be clear, the OEM valve operation ceases to exist, but there's a FVD valve system that replaces the OEM that maintains the functionalty of the button on the console? Or no more valves and hence constantly / always open?

Money2536

Cargraphic has a valve replacement solution, but FVD currently does not. FVD makes a bypass (much like Sharkwerks), or they have a center muffler replacement. You can then pair either of these options with lighter weight, higher flowing side mufflers that delete the valves. I don't think we would have the option to keep the stock valves, but I'm not sure. Rhonda was certain that there won't be a drone. There should be a deeper growl at lower RPMs and a bit more nastiness at WOT.

You know me. I'll take tons of photos and video of what I figure out. I'm losing the PSE button functionality, but I have already lost that with the disconnecting of the valves.

I still think Cargraphic is going to be a decent valved option if you can control the valves manually.