I've got an '02 XKR and I'm wondering about doing up the exhaust. Elsewhere people write that such an exhaust will increase fuel consumption.
Will the reduced back-pressure from the exhaust reduce compression and performance?
I'm aware I may be giving away quite how amateur a mechanic I am!
Thanks in advance
Luke

 

You're in the wrong Forum. This is the X150 Forum, for 2006-2014 aluminum XK/XKR models. Your 2002 is the previous generation 1996 - 2006 X100 XK/XKR Forum.

And yes, reducing back pressure will reduce low-end torque.

 

Read this: New Members - Must Read!

 

Cheers for pointing that out and answering the question Stuart. I can't see any way the X150 would differ to the X100 in that respect. I must have clicked the wrong button, I knew I wanted the X100 forum.
The question that leaves me with is why do so many people do it to so many cars?
I'm a biker by vocation, I also have a trike with a motorbike engine.
🤔

 

Reducing back pressure will reduce torque, IF YOU DON'T TUNE FOR IT.
It's all about the tune.
Zero back pressure is your absolute god, as long as the tune is set for it properly and your intake can deliver what it must also.
With zero back pressure, the combustion fills completely with fresh unburnt air and fuel.
It's the tune.
It's ALWAYS the tune.

 

The car will drive like a dog without a properly designed exhaust. I tried the free flow exhaust and it was awful.

 

As the old statement goes, a supercharged engine's an air pump, balance what goes in to what goes out, balance timing with air fuel ratios and you'll have more power... either re-map the PCM or use a stand alone.