Hi there


My car has fabspeed airbox modification along with a BMC panel filter, so a little improvement on the intake breathing.

My car has PSE which is set to always on by disconnecting in the engine bay.


I keep looking at the stock 997.1 C2S headers and they look so restrictive and the X51 headers look far better flowing.


Now I've searched and searched but no one seems to comment on if there is any performance improvement from the X51 headers or not. So those of you who have had X51 headers installed, what are your thoughts, any sound change, noticable performance gains etc? Has anyone ever dyno'd with X51 headers?
Or any numbers from track where the X51's have given you better track results?

 

There is restriction at the Cats and the headers so a lot of us do both at the same time. You maximize the improvements of an exhaust mod by doing an ECU flash so your engine can make the most out of the extra flow. But even if you do all this the noticable gains will be small to modest.

 

The X51 headers or any added headers for that matter will not add any significant gains. The X51 headers shift the torque curve about 6-800rpm to the right so you make peak torque at a higher rpm. If you spend time in the upper rpm ranges you'll notice them. As for sound they change the tone very slightly deeper. You will barely notice it with PSE enabled full time. I like mine and am glad I did them. The stock headers on the 'S' model are pretty bad.

 

So are you saying you lost low down torque then?

Or did you get more peak torque but higher up the rev range? Did it make it more enjoyable to drive when on it or actually quicker would you say?

 

Unfortunately I don't have before and after dyno's to see exactly what changed. The information I provided was from research I had done at the time specifically to the X51 headers.

I did not notice any loss of torque down low (the 3.8L has plenty) but felt more pull around 5000rpm. I don't have the specifics in front of me but from memory it was something like peak torque @ ~4600rpm for stock and peak torque @ ~5300rpm with the X51. Not a higher peak just a shifted peak.

 

Let me know what you will end up doing... I am thinking about the exact same thing.

 

Frankly, I would not just swap out the headers, but would also do the cat's. I think you will be more satisfied with the combo of the two just from the sound factor alone. Like others have stated, there is minimal gain in swapping the headers and even the cat's and headers. But the sound performance it's vastly improved.

 

I agree. When I put X51 headers, PSE and high flow cats on my last car (T4S), it sounded great.
While we all think the stock headers look bad, there is really nothing wrong with them.