Hello everyone,

I recently installed an exhaust on my 991.1 S. Im fairly certain it has a minor leak due to black soot leaking from a few connection points on startup, (ill have to lift it back up and retighten it this weekend) however I have noticed a considerable power loss based off my butt dyno. My car used to kick my head to the back when I floor it, now it seems to hesitate and even when I have it in manual mode, flooring in 2nd or 1st doesn't seem to produce the same power it once did, despite a roaring exhaust.

Could a minor leak really be causing this noticeable loss in power? or could something else be going on?

Thanks!

 

Something else is going on.

Exhaust leak between flanges in N/A car would not be leading to what you are experiencing.

 

yeah, I figured, maybe its because I just started flooring it to hear that new exhaust and noticed the power loss

Any ideas as to what could be it?
My MPGs have also dropped, but again I have been flooring it to hear that exhaust recently so that might account for it

 

This is my first winter with the car, could the cold weather have anything to do with it? I bought it recently, haven't gotten around to changing engine air filters or spark plugs, not really sure if they were changed out at the 40,000 mark, car has 65000 miles, bought it at 57,000

 

Get a code reader, and scan for fault codes. You might have failing coil packs to a faulty high pressure fuel pump. Hard to tell.

 

Is there a CEL

 

FWIW depending where you live, 'winter gas' and cold temps will yield worse gas mileage.

 

New exhaust, leaks, loss of power? Its the leaks for sure. OP said he can see them. Id check all connections on install and go from there.

 

So after some research, it appears that loss of low end torque is normal after installing a high flow exhaust on our cars?

I took it out for a test drive just now and realized all the power seems to have shifted to a higher RPM range. The initial off the line "oomph" is gone, but after about 4000rpm it hits hard.

Anyone else with an aftermarket exhaust experience similar effects?

Im thinking about either going back to stock, or adding headers to see if the low end torque comes back or improves. I love the sound, just want the low end torque back

 

Kind of odd that you are experiencing that. I didn’t add an exhaust to my 991.1 S, since it has PSE, but I did install the SOUL headers with high flow cats and NO tune. I was hoping to bring up the TQ/HP, in the flat spot that’s around 3.7k-4.3k. To my surprise, my low end TQ gains where anywhere from 20-40TQ at wheels mostly throughout from 2k-4.5k, and about 10-15WHP, the gains were seen across the entire RPM band, and again started gaining more at 5k to close to redline. I didn’t expect to feel the difference, but it is positively there and the Dyno proved it. I would do a tune to extract more power, but I’m pretty sure I’ll be selling the Car for something else 😉

Which exhaust did you get?

 

Jason Fenske of ENGINEERING EXPLAINED has a video that covers the subject of “back pressure “ and “scavenging” on exhaust systems.

Per Jason, roughly recalled, best to watch the video.

On NA engines, if the diameter of the exhaust pipes is too large, it will interfere with the velocity of the exhaust gases and the pressure pulses generated during combustion. These systems are tuned by the engineers and changing components will give different results.

Could explain your low end performance, the engine has to spin faster to get the exhaust velocity up and your power band has shifted.

 

I think that’s what’s happening to me. I’m surprised I can actually tell a difference.

I don’t track my car and I live in a city, so I use a lot more low end torque than high end. I can’t really have too much fun in the upper end because the car has a tendency to hit “go straight to jail” speeds fairly quickly in the upper rev range.

I installed a pretty popular high quality exhaust based on the reviews on this forum. I love the sound, but just am a little disappointed with the loss of low end torque.

Would headers fix this issue?

 

Yes they would. Usually the short length headers provide more power down low and long tube headers up top. My headers did it at both ends, actually all through out.

 

which headers did you get?

Im looking at the soul headers right now

 

We're beyond thrilled to hear about your experience! Let us know what's cooking for the next project!

Thank you for considering us! I invite you to give us a call and chat about your current situation and how we can make sure your next step(s) get you the performance, sound, and driving enjoyment you're looking for. John Gaydos would be more than happy to take care of you.

-Mike