Jimmy-D

So- If you remove side mufflers, which has obvious benefits- what is the downside and do the outweigh the benefits??

- Drone is one I have heard and can be pretty significant but every one's ears hear things differently. What can be intolerable to one may be unnoticeable to another.
- I have heard big loss in low-end torque - true???

** Be interested to hear form others' regarding this set-up

juanpablo046

This is 100% accurate.

The central muffler has two different piping inside for positions of the valve, but the valve is not on this muffler. The valves are on the side mufflers hardware, f you remove the side mufflers you end up without it and will be forced to choose one of the conducts. You are saying you end up with valve system but it is because you add an aftermarket valve, which is different.

You can clearly see the valve system in this picture.

If you delete the side mufflers you delete the oem valve system, period.

CAlexio

I think you're confusing removing side mufflers with removing the cats like the Dundon system. You can remove the side mufflers but leave the cats which I believe is what this tpc system does. No question that for those of us who haven't seen these systems compared, the gt3 setup seems mighty confusing.

I've read every thread I could find, and still don't have a clear sense of how each system is made. This is why I haven't purchased on yet.. I'd be guessing.. and when you add in classic forum issues with people making bold statements which are factually wrong, then decisions become even harder.

From what I can tell there are

-center delete (no power, louder, no drone, cheap and easy to install, no weight loss) . Keep sport exhaust function. Some sound differences between brands.

-side delete but keeping cats like TPC, which takes away valves for sport exhaust but then maybe replaces them with aftermarket??? Can't tell here.. does exhaust button still work?? small power gains, 40lb weight savings, heat reduction benefits, sound quieter than center delete??? California emissions compliant?????

-full system like Dundon, no cats.. non-emissions compliant in CA, big power gains.. I don't know the rest.

-too many brands with conflicting designs and claims to even begin comparing properly.

I'll wait until I see more reviews.. car sits in Europe waiting for my return anyway.

juanpablo046

I think I can help you a bit:

OEM exhaust is separated in three parts:

1) Header including the cat
2) Side muffler including the valve
3) Center muffler (tips are actually removable)

-center delete (no power, louder, no drone, cheap and easy to install, no weight loss) . Keep sport exhaust function. Some sound differences between brands.

I've seen this in different GT3 and GT3 RS, works very well, low to no drone, cheap and you keep the OEM valve system and button.

-side delete but keeping cats like TPC, which takes away valves for sport exhaust but then maybe replaces them with aftermarket??? Can't tell here.. does exhaust button still work?? small power gains, 40lb weight savings, heat reduction benefits, sound quieter than center delete??? California emissions compliant?????

Removing the side mufflers you end up having to use a more expensive part to keep the valves (new valve system like TPC) or you can use a simple pipe and just use one of the mufflers piping (like the Akrapovic Sports Cup Line). If you want the button to work you will need extra hardware with valves, remember that. You could have some drone at low rpm.

-full system like Dundon, no cats.. non-emissions compliant in CA, big power gains.. I don't know the rest.

Full system with high flow cats + software will give you significant power gains. The car will be loud.

-too many brands with conflicting designs and claims to even begin comparing properly.

For 991.2 GT3 Akrapovic will come up with a model-specific system very soon, that's what I will use in mine.

mass27

I think it has been proven that the PRIMARY reason for purchasing an after market exhaust is sound. Like you, I find the myriad of choices dizzying, with conflicting dyno results and holy Christ I have to read another thread on exhausts and use my decoder ring to determine what, if anything, is accurate. Due to this, I THINK the smartest play is the center delete. All other options are more expensive, more CEL, more torque, less torque, more power, less power, less weight, less calories and any other more/less that someone will claim to have achieved.

cox1974

Fantastic reply

CAlexio

Yea mass nails it.. I might just stick with center delete and avoid the heartache. I Have a GPR-type sitting in garage for when car returns which was donated to me, I'll just try that first until o get some really compelling evidence why something like the TPC is worth it. The full Dundon-type is too extreme for my uses

cox1974

I still have no car... But already have a SW bypass in my garage... Ahahahah

Jimmy-D

I have a GRP on mine and vacuum lines plugged so no more valves. I am very happy and I am glad to be done with any Mods. I do not need this car any faster and love the sound. Loud but tolerable. Does not sound as good as my previous GT4 but louder and more GT3 sounding any way.

0to60

Heard my neighbors stock GT4, sounded better than my .1 GT3
I didn't expect a GT4 to sound better than a GT3, but it did and I don't know why.

Jimmy-D

What it lacked for in power they made up in sound. It sounded a lot quicker than it was but that was part of the experience. You could wring her out on the street which made it a little more fun than my .2 GT3 but still having those additional 100 HP underfoot too damn fun even though you have to be more diligent /respectful

Alan C.

You should hear one with a set of Dundons.

Golden Boy

rosenbergendo

There is def a weight saving the center delete such as GMG bypass.

CAlexio

Yes.. somehow that midengine setup sounds amazing. My spyder with sport headers sounded fantastic to my ears.. way better than my gt3. Soooo... hoping one of these exhaust setups will change this.