In my frustrating journey to improve the exhaust note on my 07 XK here’s what’s happened.

1) Car sounded great when I bought it but found out I had a leak at the exhaust manifold. After tightening car became silent.

2) Deleted rear box and absolutely hated the sound. Sounded like a motorcycle almost. Very loud and obnoxious at hard acceleration.

3) Installed an XKR rear box.

The problem is the car is back to sounding silent. It has a very faint exhaust note but sounds the same as with the original muffler. At idle I checked the exhaust tips for air flow. The two in the middle had lots of exiting air. The outer two felt like minimal if any air was escaping. My understanding is the valves have to be open since my car is an XK.

So I’m thinking either the XKR muffler just doesn’t sound that different (which is out of line with multiple reports on this forum) or somehow enough exhaust isn’t leaving through the outer two pipes.

Anyone with fuse 19 pulled on an XKR or with an XK with XKR box know if a lot of air should be exiting the two outer pipes at idle?

Is there supposed to be a noticeable difference with 19 pulled or with this box on an XK? Thanks!!

 

Sounds like the valves are closed. Internal springs should keep them open when no vacuum is applied, so either the valves are stuck or the springs broke. You should most definitely have more exhaust flow from the outer pipes.

 

Thanks KJ.

 

I’m thinking since this exhaust will only be used on my XK could I just have the valve area circled in yellow cut out and replaced with new pipe? Wouldn’t this essentially eliminate the valve and provide the same result as an open valve? Or is there an easier way to reach in there and open the valve? Thanks!!

 

Use cable ties on the exhaust valve actuators to hold them permanently open

 

Yeah, Steve is right. It’s been awhile since I installed mine, and forgot it’s construction. Since the mechanical control is accessible outside the pipe, you can move it yourself to see if it is functioning and tie it in the right position.


Valve mechanism is exposed.

 

Thanks Steve and KJ!

 

And what centre section have you fitted, the stock XK one or an X-pipe? Eliminating the stock resonator will help open up the note a bit more.

 

I still have the factory center resonator. Was planning on switching to an X-pipe as close to the cats in the front as I can. Like this.

 

Took the advice above and sure enough the valves were closed. Used some wire to hold them open.

A significant difference in sound than before.

For the benefit of anyone reading this later, I drove the car for a bit with the factory center resonator and the XKR back box. Then I swapped the center resonator for an x-pipe. The x-pipe was installed where the center resonator was.

There IS absolutely a significant difference in sound. The car is quieter than before but the tone is totally different. It does sound more refined and higher pitched. That said it’s not quite loud enough. I’m going to digest it and then either keep it as is, go back to the oem center resonator, or keep the X but change to lower cell cats.

My take is that the sound achieved from the x-pipe plus XKR back box PLUS 10-20% more volume would be ideal. I’m guessing the cat change might achieve this. Either way I’ll report back.

 

Something that just came to mind… the XKR backbox, with the valves open now, still has a significant portion of the exhaust going through the quieter inner pipes. For grins, try blocking the inner pipes (stick a potato in them, just kidding ), and see if the volume increases.

 

X pipe will only vhange the pitch/tone make it sound more like a flat plane as opposed to a muscle car sound it won't increase db.

See how you go with it if you like the sound great if not swap your cats out Ive got 100cells however I'd recommend 200s that would be 👌

 

I love how mine sounds after building the system.

 

When you finally get that right exhaust note ahhhhhhh !!!!

 

I feel like I have found the perfect note but the volume is turned down. That’s why I’m thinking 200 cell cats will turn up the volume without changing the note.

Thanks for all the advice, y’all are awesome!