Drifting

I've noticed a few people putting new headers and cats on their 991 GT3s.

Two questions

1-is there is good and reproducible data on just how much of a hp and/torque boost u achieve by doing so on the 991 GT3?
I would think Porsche would have maximized the GT3 engine, more so than a regular 911 or Cayman engine.

2-What do we know about warranty coverage on GT3s with modified headers/cats?
It appears to be safe to exchange the center muffler for sharkwerks or similar exhaust, but I really wonder if your claim for major engine repair could be denied if you've installed your own headers/cats.

rockitman

I wonder how the new dual lamda exhaust senors are handled ? If I do anything, it will be the sharkwerks bypass for the 3rd muffler only.

rosenbergendo

This!

Jimmy-D

I know some others' have installed after market headers and Cats. I think I would like to see what HP and Torque gains compared to stock. If greater than 20 hp may be something to consider. If 10-12 hp not really going to make a difference for me who does not track.

Now - yes - Porsche would have to prove, if an engine issue develops, that it was related to the after market Headers and Cats. But, if they are swapped back to stock before diagnosis- they may never know. But I do not know if they pulled the software if it will detect something fishy.

rockitman

I would think 20hp increase would be possible with finely tuned header, cat, muffler synergy. Does the car need it ? Not if you are not going to PCA club race it, IMO.

Slip

With a reputable brand of headers the sensors will reconnect as per normal and there are no check engine lights. The cargraphics ones that I installed in my other post are like this.

rockitman

This is consistent with my europipe experience for my 996, but did not change the stock headers. I mustang dyno'd in the summer at 377rwhp. For the 996

Drifting

I think the car needs torque more than horsepower. I don't think anything would produce a noticeable increase in torque other than increasing the displacement, (4.0 in the RS)

I've decided not to bother with spending money on headers and cats for minimal hp gains and risk non-coverage on the warranty.

rockitman

I agree, full exhaust system changes will not be in my future. I may try the sharwerks third muffler bypass though.