MarbleNY

Don't let your wife interfere with car mods.


Hahaha, in all seriousness, i have soul cats and bypass pipes and then I installed headers. If I did them all at the same time i would've saved a bunch of bucks. With a pro tune my car is putting (this is off memory) about 475WHP. At Limerock today a 992 Turbo S definitely had me by a a little bit on the straight but the 991.2 Turbo S couldn't gap me. (I ultimately smoked them both through the turns though). The combo is the best bang for your buck mod for a 991.2

cutlass476

Legitimately, what kind of power increase am I looking at with Soul or Vektor sport cats and a COBB Stage1 or Stage 2 tune? Anyone have first hand knowledge...reliable, uncooked dyno runs?

Sarawnty

I don’t think there’s right answer as to which to do first. I did the Soul sport cats first because I found the stock PSE exhaust too muted for my liking. I then installed Vektor headers primarily because I didn’t like the design of stock manifolds (even though some say headers don’t increase hp). I wasn’t expecting a significant power increase from either the cats or the headers. But my wife immediately noticed the improved sound quality with the equal length headers. The two main reasons I went with the Vektor headers were the ‘equal length’ header tubes and the collector design. However, by far, the most noticeable power increase came from the tune. I’ve also installed BMC air filter, Vektor AOS and EVOMS diverter valves. IMO, the mods now all work in perfect harmony and I have no plans to changing anything more in the engine compartment.

VektorPerformance

We picked up 44wtq and 28whp with adding a Cobb stage 2 tune + HF cats. This was with our headers already installed for the baseline.

I'm 90% certain I have a cats/tune ONLY plot too, but I am not in front of the dyno to look it up at the moment.

F355bob

How much of that increase is the tune and how much increase are the cats? It seems some people are saying headers alone don't do much. It seems you need to do a tune and then add headers and then add cats and dyno after each mod to see what the improvement is.

cutlass476

I would love to see that plot. I have a COBB Accessport coming. I am planning on cats and a tune. The headers seem like a lot of work and expense for not a lot of return, which does seem strange to me because the factory manifold design looks horrendous and seems like it wouldn't flow well at all.

VektorPerformance

Mostly the tune, and by a good margin. No bolt on product is going to increase boost and apply more aggressive timing.


It's bit all over the map. There are different header designs out there, different model trims, different mods, different levels of change sensitivity (to sound, power, response, etc.) and few that have a dyno plot showing before/after with a header being the ONLY change. You can find similar variation among other mods as well.


Correct. A process few follow because of the time/expense involved.


Headers absolutely make power. There's a reason Porsche updated the design and the new models make better power. With the 991.2 the log style manifold is terrible. Changing to a well designed equal length header improves the volumetric efficiency of the engine. You can see it in the ECU feedback; throttle position adjustments, WG duty cycle, and boost. In fact, once the ECU relearns, you can observe two things. Power after installing headers increases, and than as the ECU learns, it starts to reduce some. Concurrently, boost can also be observed to be slightly lower. What you're seeing immediately after install is that the old target boost is making really good power, but the ECU recognizes over cycles, that target power/torque values are being exceeded, it starts dialing variables down. This is why to fully take advantage of headers, a custom ProTune needs to be applied to increase the allowable power/torque tables, so target boost can be obtained.

Stage 2 tunes are typically specifically for HF cats. Likely because HF cats are far more simple and similar to each other. We have discussed custom Vektor header OTS maps, but headers are often later on the mod path list, so there can be more variables in play. Plus again, 3 different trim levels. In short, it just doesn't make a lot of sense.

All that said ^... never take the advice of the guy that makes/designs/sells the parts word as anything than biased. Due diligence goes a long way to making a decision that best suits your specific needs and wants. There are many well written reviews, install guides and so on that can guide your choices. For anyone local, or willing to make the drive, bring your car on down and if it doesn't make power on the dyno using our headers, we'll issue a refund for the headers.

spdracerut

From observation for a while now, caution needs to be used in comparing dynos on a stock tune car. From what I can tell, the ecu is exceptionally good at hitting the load targets programmed into the tune. The ecu tries to make the car drive the same in as broad a range of conditions as possible. So it adjusts boost/timing/etc based on ambient temperature and air density to try to make the same power in all conditions. There are limits of course. Anyway, when improved breathing mods are installed, the ecu does seem to do a self learning over time. So, if you dyno right after swapping parts, it will not have time to self-learn and adjust and the result will show differently than after the ecu has had time to adjust.

This is the dyno from Fabspeed of their headers. For all intents and purposes, the torque is the same as stock up to 5500rpm. The headers are a breathing mod and should show improvement everywhere. For the torque to be essentially the same tells me the ecu was adjusting.


This dyno is from the MotoIQ test of the Vektor headers. MotoIQ did a whole driving procedure after installing the headers to give the ecu time to self-learn the new mods. Again, the torque was basically the same up until about 4500rpm. I would chalk up part of the difference being due to different dynos and airflow setups. https://motoiq.com/testing-vektor-pe...911-carrera/8/



While the ecu is good at hitting a torque target, breathing mods should enable the turbos to spool better and MotoIQ was able to measure this.


Some butt dyno and other observations speaking to quicker spool:
https://rennlist.com/forums/991/1102...l#post15349903

This is a dyno from Soul, and their design is very similar to Fabspeed, so I believe the performance would be essentially the same. Two differences: this car had a Cobb Stage 2 tune on it and I think they did back-to-back.
https://rennlist.com/forums/991/9992...l#post16996356


For sure, a tune on a 991.2 is the best bang for the buck. If you want better spool and power and sound, sport cats and headers both do it. Sport cats add way more volume, headers (especially equal length) clean up the tone and sound. Most people are very happy with all 3.

cutlass476

thank you to everyone for all of the input and sharing the plots. I am definitely doing sport cats and Cobb tune. I’m thinking about upgrading my accessport to include the PDK tune. So I will have sport cats, Stage 2 engine tune and PDK tune. Should make the car much better driver. After this, then the DSC. I have it on my 997.2 and it was awesome.

VektorPerformance

A couple photos of our high flow cats with HJS cores and large diameter mandrel bent outlets welded by our team. We often hear from our customers about the quality of the welds and it is really a testament to the care our team puts into their work.

joe084S

I did SOUL Performance headers first because the cats took longer to make. The headers alone change the pitch of the exhaust to be a little deeper and better sounding and the car's power delivery feels more linear with better spool and less lag. The cats get you even more sound mainly cool turbo noises and pops and bangs.

You will enjoy the high flow cats more as a sound difference so I would do them first if you are limited on the budget. I ordered the headers, high flow cats, air filter and APR tune all at the same time. If you can do it all I would say do it all lol. Complete different car

cutlass476

Just picked up a pre-owned Vektor set from devtec. He only had them on his car for ~75 miles. Decided to go back to just headers. Can hardly wait for them to arrive. Will put them on next weekend along with my Rennline radiator screens.

Cats look great and appear to be first quality.

BTW, I like your company slogan. I have been saying something like that for decades. “Excellence can only be achieved through the relentless pursuit of perfection.”

VektorPerformance

Thanks. I've been a fan of that statement as long a I've been an engineer.

For those asking about a headers ONLY plot, here's Cobb AP Stage 1 without and with Vektor headers added. This is on our shop mule C4S...

VektorPerformance

We are excited to hear your impressions once you get to drive them!