cutlass476

Hey guys, I'm considering headers and high flow cats. While I would like to do both all at once, the budget (wife) probably won't support both at the same time. Soooo, which should I do first to see the biggest performance improvement.

I have pretty much decided on the Vektor headers and either Vektor or Soul high flow cats. Also, I still haven't ruled out Soul Cat by-pass pipes with O2 spacers. Anyone running the By-pass pipes, can you provide feedback on CEL issues or not?

Thanks again.

mc3456

Find a way to get both the sport cats AND headers. Don’t forget the labor cost of removing/installing the rear bumper (twice!). Partially offsets the cost of the other item. If installing yourself, then disregard suggestion and accompanying rationale (for your wife).

wearegiant

Are you a 991.1 or 991.2?

991.2 You can do them seperately. However on the 991.1 they're 1 piece

isugoo

for your 2019 991.2, they'll be separate pieces.
• Sport Cats: best sound and good performance gain by removing restriction but depends on your state regulations, it may not pass smog.
• Headers: not much of noise gain from what I hear but change the tone nicely. so you're buying more for minimal performance gain alone, no issue with smog test anywhere in US.
• Personally, if you're going to end up getting both, do both same time, you will save at least 20-25% labor doing both.

cutlass476

Thanks for all of your input. It appears, from what I have read, that Sport Cats/By-pass pipes offer the biggest improvement. I'm guessing with both equal length headers and sport cats (along with a COBB Stage 2 tune) I will see the greatest increases. Both the stock headers and stock cats seem really restrictive, which just chokes a turbo motor.

737gdog

I did both last month. Soul cats and Kline headers. If I had to choose I would start with headers. Cats are obnoxious in sport mode for my taste unless on a track or in the mountains having fun. Personal opinion of course as some probably really enjoy the increase in artificial noise. Happy with Soul and Kline however and recommend both.

forbiddenbeat

This is awesome to hear, as I'm planning on only doing Kline headers. Don't want the car too loud, mostly just looking to get rid of the garbage stock manifolds.

VektorPerformance

If the car is non-PSE, the bumper can stay on

With PSE you can drop the muffler/cats together and make the swap on a bench, but it's highly recommended that you recruit a friend to help with the heavy work.

HF Cats, headers, and tune is a BIG kick in the pants. You can't not notice how the car has MUCH more power.

If there's any questions we can answer in regards to Vektor products, please don't hesitate to ask

cutlass476

With that understanding, if I was only going to do one at a time, which should I do first? HF Cats or headers? I have a COBB AP coming.

My car is PSE, but none of the install videos I’ve see required the bumper to be removed to install either carts or headers. Rear wheels yes, but not the bumper. Is bumper removal necessary?

VektorPerformance

Always a tough question to answer. It's so subjective and everyone has different goals with their mods.

For me, here is what I'd do if I had to take those steps over again...

I'd start with the headers. They are not the biggest performance bang-for-the-buck, but they do improve drivability. Most of all, the sound changes. You'll hear a bit more turbo whistle, the exhaust is more crisp, less muddled, and the tone changes. Others have described it as more "classis Porsche' and I would agree with that sentiment. Next would be the cats WITH tune. I say with tune because changing both headers and HF-cats is a decent change to the engine's VE. Not enough to cause any problems, but not in the middle of the OEM tune's operational sweet spot. Not only that, but the added tune will also take most advantage of the mechanical changes that have been made, for both performance and reliability. On the cats, it adds volume to the soundtrack. So when doing both at the same time, it's a decent overall change. Most all enjoy it, I know of one instance where the customer went back to only headers after feeling the cats added too much volume.

PTS-BRG

Shameless Plug... I have a full Kline system for sale on the Rennlist market place with headers, Cats and muffler

As someone who has done it all and had the same 991.2 with PSE, I think the cats make the biggest difference in power and sound. If you are doing both I would do cats first.
If you are NOT looking for a big difference in sound then do the headers first as the sound will be deeper but, not louder.

rugu6869

I have the Soul Headers and Sport Cats. In no way do I think the car is too loud (in Sport/+ mode).
Cruising on the highway at a constant speed you can barely hear the exhaust. Put it in normal mode and you only hear wind/tire noise.

Sport cats will give you the most bang for the buck. You live in Florida so you could just do cat-bypass and it'll definitely be louder and you probably won't even have to do headers (plus the cost of the cat bypass pipes are much cheaper to start with).

I realize everyone is different when it comes to sound. For me, the headers and sport cat combination is really good with the stock PSE. I'd like it a little louder in Sport/+ mode to be honest, just as long as in normal mode it would be as quiet as stock so the family doesn't complain when we're in the car together.

Jeahbladejeah

It's not necessary, but from what I understand it makes accessing the heat shield and O2 sensors that much much easier. And it's very easy to remove so most will just do it anyway.
I did a cat and header install myself without removing the bumper and I'm not a highly skilled mechanic.

VektorPerformance

Removing the passenger side wheel help me most with access to the heat shield. I don't know if bumper removal would have been better, it seems like with the wheel removed the tool had a straight shot. Some install variations likely have something to do with tool selection as well, or lack of one. The guy across the alley from us who only works on high end specialty stuff has ALL the tools. We have a decent selection, but not anywhere near what a tech would have.

Of course another layer of variables are that the trim levels all have slightly different turbos and/or rear fender widths. How much that comes into paly here on these parts, is anyone's guess.

B Russ

I did soul cats and thats where Im stopping. More than enough sound and performance