I hate to stir the pot but I have to let you guys in on something that we've know for a while and even built a set of headers on our 996tt to prove the fact.

Headers on a stock based turbo do nothing!!

Years ago when we were developing Mitsubishi EVO headers we build a really nice large diameter header for a 400whp EVO VIII we had here. They did absolutely nothing, maybe 2 to 3 horsepower but nothing you couldn't attribute to standard dyno variance. The only think it did do was create lag from the large runners.

Now on to the 996tt headers.

We designed a nice set of headers with cast merge collectors and a cast head flange that has a smooth transition from the exhaust port to the tubular runners. After fitting them to the car and doing a direct back to back test (same day) the results were as expected, no real measurable gain. at 650wph each run was 5-10 hp in variance and there was no real measurable difference in the power level from the headers. The headers are larger internal diameter than stock.
The thing with turbo cars is that you can get away with a much more compromised header design than NA cars. As long as your exhaust back-pressure is significant you really won't benefit from a well designed header. In my opinion, until you get away from stock style turbo's and over 750whp it's better to stick with stock headers, otherwise it's just a waste of money. Better spend it on a turbo intake system, intercoolers, tune, etc...

I know this may create some heated debate but it is what it is and I'd rather see owners spend their money on parts that work and make horsepower.

-Martin

 

Thanks for the truth instead of the hype.

 

The only problem is that we have known this for years, its not news. Headers only matter after you have upgraded turbos, exhaust, etc.

 

Yeah, headers are pretty much regarded as useless already.

 

Well that good! Our 996tt has all those upgrades and it still did nothing, unless you're going with a GT30R based or bigger turbo there is no point to upgraded headers.

 

Good thread Martin. Though it is generally known from some of our posters that have been her for awhile, you still see a lot of post almost weekly with people asking about headers. Then they always argue that they are going to help because it did on their N/A car.

 

Thanks for the independent test! Are your stock headers ported?

Edit: In my book (whatever thats worth), this speaks volumes about your trustworthiness as a vendor!

 

Anyway we can get you to post the back to back graphs?

I am curious if it changed the spool up time?

I am planning on doing 30 based turbos here shortly and I still see no reason to go with aftermarket IMO. Stock are nice and you dont have to worry about cracking.

 

Wait!...but I just put new headers on from eBay...and my butt dyno definately feels the advertised 20 extra horsepower...and the turbos spool up faster too! lol...

 

in k16based turbos there is not significant gain...however as you go with bigger turbos,spool up time is less with headers...

 

Actually you will see some gains at the 24/18 level...BTW, we are looking forward to your billet 24's, how are they coming along?

 

the test was done with k16 based turbos and it puts out 650whp?

 

Port/polish stock headers. (I'm excited to hear news of the billet 24's as well.)

 

https://www.6speedonline.com/forums/...illet-k16.html

 

Kevin has been saying this since the year dot!