Mike S

For those of you with an Speed Force Racing full system or Cat-back, I've got some sound test results for ya.

I'm currently running a full SFR 3" Exhaust, with the Borla Muffler. All testing was done with a sound meter 3' back of the exhaust at 3,000rpm.

Test 1: SFR, No Catalytic Converter, Borla Muffler
108dB

Test 2: SFR, SFR Resonator, Borla Muffler
96dB

That's a full 12dB drop due to the addition of the resonator. The sound is much more tolerable now at full rip...perhaps even a bit too quiet, but I am very pleased with the results. Extra thanks to Tim (SpeedForceRacing) who convinced me to abandon my idea of adding another muffler and suggested the resonator instead.

Mike1982

Sound clip??..

rcatherton

I have the SFR 3" exhaust with the resonator and it is tame. No poping or tin can sound. The resonater is louvered and as a result they do extend into the airstream necking it down to about 2 1/2 inches which does appear to be a bit restrictive, but Tim said he tested several and this one had the best sound. The resonator is very heavy compared to the rest of the exhaust components and I would prefer a straight through perforated resonater like the one shown by David Floyd in this thread that was lighter. If I knew the sould was not out of hand I would probably change.
https://rennlist.com/forums/showthre...hlight=exhaust

IanS

Wow, 106dB is loud. Is that almost as loud as no muffler at all?

danny951

wow.. that is loud. I haven't put my fabspeed on yet. It will have no cat and just the fabspeed muffler. I do have access to a sound meter though so I will try to mimmick your tests and post the results. I just got my new tires and my wheels mounted, so I can get my inspection done, and then get the new exhaust put on. Should be next week.

Porsche-O-Phile

106 dB (I'm assuming that's a dBA not a dBC measurement) is loud. That's also at full-bore, which how often do you really do that? Personally I'd say even that loud is fine as long as the more "normal" throttle position dB numbers are reasonable, seeing as that's where 99% of your driving is going to be anyway - except for the track of course and there, who cares how loud it is?

hally

how does a resonator flow in comparison to an aftermarket cat converter?

tedesco

Also seems very loud to me. I am running a full 3" as well (no cat) but unfortunatly with some kind of custom mufflers (don´t know exactly the specs). I got them from a german dealer how produces them himself. The mufflers are straight through designs and I installed a small one where the resonator used to sit and a bigger one at the back. Dimensons are:
small- diam 150 by 200 length
big- oval 200 wide, 140 high and 400 long
It is equal to marginaly louder than stock at idel and getting a bit louder than stock at higher speeds. I have got a direct comparrison because I got another 951 with completly stock exhaust and CAT.

Mike S

Yeah, its dBa and it was 106 but remember that was at 3,000rpm. At 6,000rpm its even louder which is why I had to quiet it down some. Those local guys who were at the Devek dyno run last year can attest to how loud it was at full throttle.

I do notice a very small increase in spool up time, but that's with the uncalibrated butt dyno so I can't say for sure. Anyways, i'm happy with the results.

tedesco

The 106 dba are one thing but the noise reduction of 12 dab (!!) is another. Very impressive and realy effective if power did not suffer.
I thought of taking the smaller 1st siencer off this weekend but now it does not appear to be a good idea any more...