pete95zhn

Hej!

I did measurements for PCF's track day about a week ago. Track has 95 dB limit (or 110 for specific race days) so all about 100 cars had to be measured. 45 deg angle from the end of exhaust pipe at 45 deg angle from the ground, 50 cm away. dB(A) and slow scale @ 4500 rpm. 991 GT3RS did 87db, valves closed.
OTH I also compared actual passing noise with the same instrument...it did 97 dB @ 3rd, floored with valves open, measured 20 meters away. Had to flag away and ask to close valves.
BTW, every other car was quieter at track. From ordinary 991/981 varietes' about 3 dB @ 93-94 to old air cooled'
10-12 dB @ 87-89!

qbix

You can't just close the valves. They will open anytime you floor it regardless of the position of the switch.

Kobalt

First: Good info, thanks!

Second: Was the 991 GT3RS louder than the 991 GT3?

pete95zhn

Didn't have any of those then, it was not so advanced's day and RS was one of the instuctor's toy. But 997 GT3 had 93 dB at pass by, 102 stationary.
But, GT4s and 991 C4S were 96-97 stationary and about 3 dB quieter passing by. Conclusions are yours...

Jamie@dundonmotorsports

The dyno jet we started on was about 15% loss to factory SAE crank HP specs. The 4000 has more loss than a 2000 and it is set very similarly to the dynojet so our numbers still mean something (at least to us).

The bottom line with any dyno is it's a tool and you have to understand the tool and what data it's telling you!

So far our testing has been shown to be conservative as cars tested on other dynos make more power, this suits us fine!

tonymission

I'm sure there's been plenty of talk about this kind of thing, but would this setup + tune give PAG a reason to void a warranty (specifically the engine issue)? Obviously the answer is technically yes, but I guess more of what is the precedent here? Are guys removing the setup prior to major warranty work? I know with my RS7 tuning, we have to re-flash the car back to stock before any service to avoid the car being flagged "TD1". I went stage 2 on that car because there really hadn't been any public issues, but if we're driving ticking time bombs here my thoughts might be a little different.

Pay to play and all that, but it seems to be a 'when' issue here and not 'if'.

Jamie@dundonmotorsports

What we've gotten from most dealers is exhausts are not an issue, tunes make them a little nervous.

So this is why 90% of our customers do just the exhaust and no tune, and another reason why it was important to us to get as much power as we can with the stock ECU. Tuning allows a greater flexibility in crafting the power.

Porsche is pretty good about known issues with engines (like the cam finger follower wear issues for example) and not giving owners a hassle about modifications to the car being the cause of them.

In the end it comes down to the relationship you have with your service advisor manager, good to check with them if you're at all concerned.

The alternative is to do what you do now and just swap it back out if they're a bit tight about it...

tonymission

Thanks for the quick response! That makes total sense and they did say exhausts were OK, but I didn't know if that extended to a full header setup. Salesmen seem to be a little more "oh yeah, of course that's fine" than maybe the official stance is. I'll poke around a little more, get to know some of the local guys here in Atlanta and figure out what everyone else is doing. ECU modifications almost always draw pause regardless of the car and/or dealership, but I'd love to unleash a little more of the beast and it seems like you guys have a great product and really know what you're doing.

Jamie@dundonmotorsports

At my local dealer here in Washington state, the techs and service manager were oogling the header design, were revving the car for the sound in the service bay and fighting with each other over who was going to do the test drive (service manager and lead tech both went). This was for a few coils that went bad and they had no issue warrantying them.

I can't say the local dealer is the norm, but they were really cool about it and genuinely excited to see a well crafted product on the car...

Macca

My understanding (here) if its bolt on and its not touching the factory ECU code then it will get by just fine. Its different for different markets of course. The issue with a flashed ECU is that it leaves traces that it has been over written, and to be fair to PAG once someone has started to change the parameters they have chosen to operate the engine then all bets should be off. An alternative that DMS offer is a complete replacement flashed replacement ECU. Its a good option but not within my budget.

The extra power made from the ECU tune over the straight headers was nominal in my opinion for the additional cost and hassle. Sure if you have the CEL light issue after the exhaust is fitted (rare and doesn't seem to be an issue at all on ROW cars like my own) then that may warrant considering it, however for an extra 10 bhp and a few lbft it wasnt a big USP for me personally.

Better yet for customers concerned about CEL or passing emissions in countries or states where this is a potential issue then the new catted 991 GT3 headers are a great alternative and they make basically the same power in any case! Better still if you "upgrade" to the 991 RS or 911R then you can take them with you and Im sure there will be no shortage of takers on the secondary market later on should you decide to try a different marque or vehicle all together...