TTFLT6

Yes, slightly less bass then with stock valve operation. YMMV

Ramon Vennik

Tip: I drove my daily Spyder from
start 2021 with catless JCR headers and lightweight competition Fabspeed catback exhaust (no silencers), and the drone was immense. Driving with earplugs was always the way to handle (no problem as motorcyclist).
When I started using my Airpods Pro v2 (not v1), in Adaptive mode I was flabbergasted about the effect. SUPER!
In noise cancelling mode it is even too quiet to my taste (never used it in my Spyder).

jm2c

Cam07

Sorry if this info is readily available somewhere. I’ve searched & can’t find an answer.

I installed the JCR backbox today thinking that I could reuse the bolts that were already in place from when the Flat 6 OAP’s were installed. However, I had an issue with galling on nearly every bolt which were SS A270 bolts. We were afraid they would need to be cut off, but thankfully they just snapped.

I’ve read where it may be good on exhaust applications to use SS bolts & brass nuts. Does it hurt to use these different materials on the titanium exhaust?

Thanks!

Westcoast

So the Flat 6 OAP use bolts instead of studs and nuts (OEM)? My Akra OAP's attach to the header flange via stud/nut as to the OAP to rear section.

Alpha Ice

I've posted here a few times, and tried to respond to DMs too, but with no valves at all, lightweight race pipe, once I'm over 2,600 rpms the drone is pretty minimal, and almost non-existent above 3k...but that's in a GTS, and I'm running manifolds, which could change the perception for other people. I do probably have some hearing loss, but we drove 3+ hours at 70/75+ mph which is right around 3k, and no issues at all with the windows up and A/C on with my wife riding shotgun. Usually I always have the windows down anyways. I noticed when I had the Fabspeed rear, that was valved, I had more drone with that in the whole range, something about the pathing of the valve system affected it (I believe the manifolds contributed some to that), but obviously this setup is a bit louder than the valved system. I am running silencers right before the cats too, so some of that probably helps to shift the sound more towards the rear of the car. I really can't explain it exactly. If I'm in the wrong gear and around 2,300 rpms then it's going to be a bit painful...I think most of us would also agree that we aren't driving the car properly if that's the case.

Westcoast

Stock headers, Akra OAP and JCR Silenced Valved Exhaust.

I detect drone from 18-2400 RPM, worse with the valves open (or lugging the engine), but with valves closed and PSE off, very minimal drone.

Avera

The subjective nature of drone tolerance is a hard factor to predict on an individual basis

I can say my set-up was INSANE . . . I doubt anyone on this forum would/could live with it for driving on the common roadways

THE problem was that I simply could not avoid that trouble range that everyone describes around 2K RPM . . . the WORST and completely unavoidable experience was at stop lights, where the engine idled in that range.

Avoiding moving through that RPM range while driving was not as simple as one might think on the common roadways. Like many on this forum, I like my engine wrung out too, so it was not simply a matter of wanting to drive in such a manner

The bottom line, in my opinion, is can one tolerate the drone or not. There really is no avoiding it.

AVM

Westcoast

First off, I agree with a lot that you are saying regarding drone... but regarding the bolded, why the hell was your engine set to idle at 2000 RPM, mine is around 800 which is nowhere near the Drone Zone!

Avera

As you (probably) know, I moved on from the GT4 . . . further, I did not tolerate the Dundon header/OAP + Race Pipe long

So, I would be the first to admit I do not have perfect recollection of all the drone zone RPMs . . . yes, there is more than one zone and my setup brought them ALL out

What I DO know for certain is that ALL of the zones were insane . . . and that idling at a stop light was unbearable

To your point, perhaps I referenced the wrong zone at idle? I would not bet my life on it one way or the other, and have no problem with you pointing out I might not recall the detail correctly

However, my statement stands pertaining to whether one can tolerate the drone/resonances . . . if not, trying to 'drive around' them is most often going to end poorly.

AVM

authenticamd

You had silencers before the CAT? Or after the CAT for the superlights as shown on the website?

I wonder if they could put silencers pre and post cat…

Westcoast

No worries and thanks for the further explanation, I didn’t know the Dundon system accentuated drone so much!

My setup is only bad from 18-2400 RPM, and only really when with the valves are open. In fact because of these posts I specifically closed the valves and turned off PSE and let the Porsche system control things and I was really surprised how civil it sounds, no appreciable drone either. If it weren't so tame and controllable I would remove it

When I am in the mood or at the track and the valves are open , drone is not an issue, 18-2400 RPM is only there for a moment during hard acceleration. I will say the on the street I am careful not to lug the engine in that range, I will downshift to bring the RPM up and out of the zone.

Avera

The Dundon headers/OAPs were not the problem. When I put the OEM rear box back on it was LOUD and void of drone . . . just did not have the RSR-like tone the Race Pipe offered

I will not digress into what has been stated a hundred times regarding all the trade-offs between decibels, tone, and drone. We know the culprits and, I believe, it has been proven repeatedly where the trade-offs (compromises) lie in the system . . .

Avera