Installed X-Pipe and resonator delete on my 5.0L XK today,
barely any increase in volume, kind of dissappointed,
actually sounds quieter upon initial startup.

wondering if there is anyway to hack the rear muffler box
to stay open all the time? (cutting out the valve etc.)

I believe the valve on the XK is pressure regulated
not electronic.
sound clip

 

If yours is the XK and not the XK-R, do you have the Active Exhaust? Two tailpipes or four? If two, you don't have any "Opened" valves to bypass the rear boxes. You would need to either get XK-R back boxes or get someone to permanently add two more tail pipes from in front of the back boxes to get any sound. Plus, then get the -R rear valance which is quite cheap.
Also, with Active Exhaust, the valves are vacuum-actuated and electrically controlled, governed by RPM and Dynamic Mode.

 

I have semi-active exhaust, (Jaguar SAM),
after looking through the workshop manual, I found out
there are 2 spring loaded check valves inside my exhaust,
I'm going to try to remove the springs or remove them altogether.

Maybe I am the first one to attempt this?

 

Option #2 is if someone wanted to swap back boxes with me?
XKR for XK

 

Not the muffler, but if you want to swap out that modified mid for an OEM XKR mid, let me know.

 

Or just pull fuse #19 from the rear seat junction box, makes valves stay open all of the time...

 

No fuse #19 on an XK.

 

As I see it you've got 4 options

a) modify original rear box (cheapest option)

b) xkr rear box upgrade (quads look unreal)

c) 200 cell cats (pricey although does free up hp 8-10whp on n/a engines)

d) velocityap rear exhaust (weight reduction, low cost and improved tone)

Being n/a I'd be leaning towards option C & D

 

Curious to what your 100cell cats sound like, any clips?

 

The 100 cell is very raw, to negate this brutality I have permanently shut 2 of the 4 tail pipes and now it's quite bearable however if I could do it all over again I'd go the 200 cell variety.

I can post up a few clips tomorrow for you if you like

 

Oh boy... Check out my rebuild thread, post 60-ish for the exhaust theory and how I redid mine.

TLDR, your X is in the wrong spot, it's diameter is too large and the pressed metal form does not do what a true X pipe is supposed to do. The X doesn't necessarily make the car louder, it should change the tone / impulses at differing RPM based on how the pressure waves are flowing through the X section. If anything a true X pipe with the 30% opening will make it quieter as each pulse can flow down both pipes instead of just one. The X pipe will also act as a scavenging motor to draw the pulse out of the off side pipe through the port. The factory resonator is just slots in the pipe surrounded by a box. The size of the slot determines the frequency mitigated and pressure balanced between the pipes.

Your pressed steel X is just a box that allows the pulses to crash into each other and sort of flow out both pipes as they want (there is not control of the pulses). The larger diameter pipe mitigates more flow so your pulses are softer and more confused. Jaguars choice to use small pipe is what gives it the raspy forceful sound at WOT and a burble down low. Also beware that free revving is not good reference of how your system works. The engine needs to be loaded for the exhaust to show itself as good or bad. Sound should not enter the equation beyond the smile factor.

 

I did the X Pipe on my 4.2 XK and thought as you it did not make any difference at best.

 

Perhaps the fuse for his active exhaust is numbered differently, I have not checked and assumed it would be the same as the XKR.

 

I was aware of the location, but not the diameter issue,
I do like the sound change i have now, but I want more volume.
thanks for your input

 

What I should have said, to be complete, is that only the XKR has an active exhaust, the XK only gets the passive exhaust.

 

I am well aware of that, the OP mentioned he has semi active exhaust and rather than checking what that was I assumed it was a special option for his car. I have now checked and this is what I found:

"The rear muffler unit includes a Semi Active Muffler (SAM) valve. This valve is operated by the pressure in the exhaust system. At low engine speed the valve is partially closed to provide a more refined noise quality. At higher engine speed the increased pressure within the exhaust system opens the valve to provide a more sporting noise. The SAM valve is non serviceable and the rear muffler is replaced as a complete assembly."

In summary it is fully mechanical with no electrics involved so there of course would be no fuse for it either. My apologies

 

I had the Mina back box installed in my 12XK and really liked the sound. got lots of compliments for the sound. Cost installed $1100.

 

for best results that x pipe should be just behind the gear box , not at mid ship . its been proven on dynos in the past . also sounds better that way.
put your center chamber back in or add two hot dogs to deal with the rasp . and shift your x-pipe forward .
mine sounded like that when i removed the center resonator and put the x pipe on my STR and swapped the rear boxes with glass packs . at that point it sounded terrible .
i then shifted the x pipe forward and added the two separate center resonators .
and that killed the rasp it sounded great . then later i replaced my cats with 200cell magna flow cats.
and some of the rasp returned . but not as bad as before . it sounds angry any ways .
the real volume is gained from high flow cats and replacing the rear box/'s with glass packs .
the center resignator in my opinion is needed as it makes for a deeper note ! these jags are raspy as when opened up too much .

 

In terms of sound, exhaust is a matter of preference and taste.
especially when it comes to tone, and resonance.

With that being said, I really love the sound of a Maserati Granturismo

Any suggestions on how to get a similar tone and rasp, and volume?


Thanks