4 Point 0

It sounds intelligent, but it isn't. The largest gain is going Catless. Catless is just a pipe. The pipe has the smallest diameter of all. (Sorry there goes his theory.) My Akra 300 Cell cats were huge. About 5 times the Diameter of the Catless pipes. The Catless pipes picked up 52 Hp at the wheels. (and that was from Akra 300 Cell to Catless)

O.P. With such a low budget, if you are not a tree hugger, or live in a state that requires the smog tests, then Catless down pipes are your best bet. Biggest Bang per buck. Going from a 600 Cell count to a zero cell count, will give a nice boost to performance and sound. If you want more from there, You'll need to increase budget and add equal length headers, like others have suggested. The worst bang per buck is the rear cans (Exhaust) Does the least, and cost the most if going quality.
A rear diffuser is just the black plastic surround (Around) your tail pipes. After market ones have bigger fins for air flow and down force. (Nothing to do with sound)

Pakman996-991.2

I have a 991.2 so I’m not sure what the gains would be for you. I haven’t dyno’d the car or have any dragy numbers but according to the SOUL website I picked up 26hp/35tq for both headers and cats. I saw another member here mention 30-40 TQ gain on a 991.1 for just the headers.

My butt dyno confirmed improved throttle response and power. I have an APR stage 1, 93 oct tune which gets me to 475 hp/460 tq + 26 hp/35 tq for headers & cats puts me around 501 hp/ 495 tq.

I plan on going catless like @4 Point 0 once I get the Tial m800 turbos

MingusDew

not really how that works, peak gains for a specific part don’t automatically stack at the same rpm with peak gains from another, but I’m sure the car is faster and overall making more power somewhere under the curve.

thesaintusa

Peak gains may occur at overlapping areas under the curve. and may not reflect peak power.

Adding mods may not (and usually does not) equal gains at peak power.

You are likely gaining power in 'usable' regions of the rpm curve.

911Raider

What’s the word with Fabspeed? Is Soul the standard for Porsche? Fabspped does not seemed to be mentions as much.

4 Point 0

Soul is popular with the bang per buck guys, if that's what is most important, than they are your guys.

If ultimate power is more important, or ultimate sound, then you need to research : - Vektor (Headers) , Akrapovic' or Kline (Cans), Tubi (Catless).

blackcheetah

I have fabspeed headers and they have the largest outlet but there not equal length that doesn't bother get some soull test pipe and keep your STOCK MUFFLER so no drone and youl have the deep sound like à na engine

VektorPerformance

Customers tell us the headers make it sound more like a Porche should sound.

Not a great vid, but shows the progression of what you've got (stock) vs Vektor headers vs Vektor headers with HF cats...

GSIRM3

This is the solution !!

Bud Taylor

What the race team tuner guy said was if you upgrade to 200 cell cats (which I was considering) and the 200 cell cats are smaller than OEM 600 cell cats you have offset performace by limiting flow which seems plausible. I did not want to go catless as i do not want either a check engine light or droan at highway speed. Is there a catless solution that offers no light/droan ?

mhconley

I'm running a Soul performance valved exhaust with their competition long tube (catless) headers on my 991.1 and the drone is not unpleasant with the valves closed. You'll need a tuner to disable the O2 sensors to eliminate the check engine light (CEL). I went with Softronic. She screams like a banshee at full throttle with the valves open.

Martin

Viper1000

That makes zero sense......the better the flow the better the power. The OD size of the pipe doesn't matter if it can't flow! Flow is what is needed!

PCA1983

Best mod for best sound in a 991.2 3.0 tt is cat delete pipes, assuming u have Sport Exhaust. U did not say.
If no Sport Exhaust, then you'll need a better sounding exhaust to go with it, plus the cat delete pipes.

Tier1Terrier

Here's my take with very limited knowledge and experience so take it with a grain of salt.

I have factory sport exhaust and I recently added soul sport cats. With the sport exhaust valves closed, the difference in sound with the new sport cats is subtle, but noticeable. Where you really hear and feel the roar come to life is with the sport exhaust valves open. Then it's a completely different beast and very noticeable. That tells me that without the sport exhaust, I might have been a little disappointed with only sport cats. So the key is either having a factory sport exhaust or going with either a trackback turbo exhaust (sport cats with straight pipes out) or having some type of x-pipe setup along with the sport cats. Going with performance headers you should expect to see even greater improvements, but again, I suspect with a factory muffler without ability to have the 'valves open' (ie muffler bypass), you will likely lose a lot of potential growl.

One thing that I don't know if it's been mentioned much in this thread with regards to going catless is the smell of the fumes. Catless with sport exhaust indeed sounds glorious but it comes with a cost. Notwithstanding the environmental stuff which may or may not matter to you, you will notice the smell significantly. In your garage or when sitting idle at a light with the windows open. It's there and it's pretty strong. Some don't mind it at all but I'm pretty sure my wife would complain about it and that somewhat plays a factor for me. And it's not something you can just turn on and off once you do it. So definitely think hard about going catless and perhaps try and find a local enthusiast who's done it to allow you to experience it for yourself before making that leap. It's worth noting that there is also an increase in the smell of fumes even with sport cats. I noticed it right away the first time I started my car. To be honest, I kind of liked it a little because it wasn't too strong and it further reminds you of the type of performance car your driving every time you smell it.

4 Point 0

As I said, it sounds intelligent but it's not. As Viper below mentions, flow is flow. The outside dimension means nothing if its corked up with 1000 cell fly screen and no air gets through. The smaller cell count will more than compensates for any reduction in outside diameter. Smaller the cell count the bigger the holes. Holes = more flow. More flow = more power and sound.
My Tubi Catless downpipes have the smallest OD of all, but the cell count is zero. So it creates the most power and the most sound. It is perfect when valves of PSE are closed, and passes the wife test. When open, it barks like a junk yard dog. No drone. I hate drone.

Exactly. 100% agreed.

Agreed. Plus 1.

I had an ///M4 and it stunk like a **** when I went catless. However, I run E40 (50% 93RON and 50% E85) and I haven't noticed the smell at all. The corn juice is far less obnoxious than Unleaded when catless.



Tubi Catless

Vektor Headers PSE