nxfedlt1

I'd like a little more volume, but not too much, so checking to see which is louder.

thanks!

Jamie@dundonmotorsports

catless headers, no drone if used with valves and the center muffler... and volume while at low load is closer to stock. When you want the system to be louder ( getting on it on the onramp or track) it is a bit louder than stock

Cay_PI

@ Jamie

When youn say catless headers + center muffler you mean also no side muffler, right? Isn't this very loud compared to stock with closed valves? I guess it may be perfect in loud mode vs. stock with open valves but with no real chance to switch it silent like stock.

Macca

I agree with this. See my review post on DMS from last week...

Remember side muffler deleted from other manufacturers generally remove the valve with the muffler. DMS leave the valve (actually they upgrade it to their own which is larger and better quality than OEM) and the twin pipes going into the third muffler so I fact the car can be made only 15% more than stock in quiet mode...

Jamie@dundonmotorsports

Our side deletes have valves that direct the gasses to the longer path of the center muffler to keep things quiet. It isn't very loud at all with the valves closed, in fact it's about the same as stock. It does get quiet and you can talk and have a phone call, in fact the tires are louder than the exhaust on the highway.

Our street (catted) system is setup the same way!

didn't see your post, Mark, thanks!

Dan@SharkWerks

I think most of the center bypasses on the market fit this description pretty accurately. If you wanted to try ours (for example) and did not like it, I can give you a 100% refund including shipping. Most people who have used ours liked that it doesn't drone and isn't too loud (especially when the valves are closed) - something the larger center bypasses are not quite as good at, and all sound great when the button and throttle are on.

Here's a recent review from a guy that asked a similar question:

IMO - if the car is not a 100% track car, I would absolutely recommend not removing the cats. It's illegal, it puts out incredibly toxic fumes that are hazardous to you and everyone around (think idling in traffic, driving in parking garages, etc.), and it really undermines a lot of fantastic engineering that's been put into modern fuel injected engines. A stock 991 GT3 is a phase I and II Low-Emission Vehicle - something I'm sure Porsche engineers are proud of on this amazing vehicle. It would be completely flipping its profile and turning back 40 years of engineering by removing the cats. Mufflers control sound, cats control emissions. Maybe I'm just an old grumpy PNWer.

bronson7

Extremely happy with mine. Just the right amount/quality of sound.

GiuseppeM

What setup do you have?

bronson7

SW bypass. Just enough loudness for an old guy.

Nizer

Well said Dan! And BTW our Cup cars use cats for the same reasons.

neanicu

Don't listen to Bronson,he's just trying to fool you,I've seen his pic and he's 38 years old.

Macca

Thanks Dan. I had your bypass before DMS headers and loved it.

As for arguments on catless race headers - I won't comment on ethical grounds, after all many of us around the world are happily running around in old air cooled cars with no smog gear at all. We are just 0.000001 of the worlds driving population!

What I will say re the 991 GT3 and DMS race headers is this:

Firstly PAGs engineering prowess Euro 5/ carb compliant or not went straight out the window for me on this car when they replaced the first engine due to rod bolt failure then the second engine was replaced by the third due to poorly designed valve train lubrication....well enough said

Secondly In Defence of DMS race headers, mine have not thrown a CEL, they leave no more soot on the rear bumper than before and remarkably I have not noticed any very strong smells yet like I've done when removing cats on previous 911s (no doubt it's there but I haven't noticed as I haven't sat idling in the garage much). In our country there are no emission tests. If there were I would have purchased the DMS catted set up...

Lastly where as the bypass was an aural enhancement the 321SS DMS headers actually add power and torque - significant enough that you notice it immediately you drive away. From a Porsche NA engine for an exhaust alone to make a noticeable difference (not just a wallet supported one) is noteworthy IMO

bronson7

Oooooh to be 38 again. All you young guys on here is what keeps me going.

Jamie@dundonmotorsports

For those that want great gains and to keep cats, our catted system group buy is up, 31whp and 25ftlbs gains for $6950.00 same price as the Race system, for the first 20 guys...