I was reading through some of the old threads which spoke of installation of X pipes but could not find any where the entire rear suitcase muffler is deleted and straight piped on both sides just past the resonators and cats. Any experience out there with this mod? Does it have any effect on blowing codes by reducing back pressure or any other detrimental results I need to know about before I remove it? I liked the volume and note when I ran it only with the resonators. BTW this is a 2007 XK with the 4.2.
Thx,

 

For me it would be to loud for everyday use but I like the sound so I have electric cutouts on mine!:-)

 

I'd be worry about not enough back pressure and car driving like a dog. I had Magnaflows installed on my XK and it was the most awful thing I have ever done. Car drove like crap; threw them into the dumpster and went back OEM.

I know the fancy exhausts are expensive, but go with a big name like Quicksilver, VAP, Larini... worth every penny and then some.

 

The back box is not hard to remove, so just take it off, forget about straight pipes for now, and just see how you like the sound. Then you can decide if it’s ‘just right’, or ‘too much’.
If just right, go with the straight pipes, or peterv8’s cutout method.
If a bit too much, consider swapping in the XKR version of the box, as several members (myself included) have done, which will then have the valves permanently open, and just ‘the right’ sound (or so I think).

 

I've no backbox on mine it came like that when purchased in 2018

Paramount performance confirmed mine has one of these:

https://www.paramount-performance.co...er-sports.html

It's absolutely fine for cruising but it will wake up people in the next street when I start it up in the early hours, so at those times choose to use one of my quieter cars

 

I've the R, so forced induction + custom intakes not really relevant to your setup, but I've dual X pipes, 100 cell spun cats and no back box, 2" to 2.5" to 3" exhaust piping. Your exhaust will be loud and back pressure may be an issue with a naturally aspirated motor with no further modifications.

 

there's definitely a loss of low end torque on the 5.0 and i'm sure it's the same for the 4.2, but i have no codes after leaving the entire assembly off the car for months. i've deemed the trade worth it for the amazing sound, for now.

incidentally still looking for someone to do a custom exhaust tail with the parts i've already picked out. kinda shelved that project for now.

i still have the muffler. i will get a few more 1/8th mile passes in without it, then put it back on and get some more in. that should be a pretty good way to quantify the difference.

 

The loss was way too much for me. Felt like a wounded dog I wanted to put down.

 

Nothing quite like real life testing interesting to see how it goes! its a shame you haven't got a 1/4 mile track out there then we could really see the traps through all the markers of the track , nevertheless looking forward to your times

 

yep i think the closest one is texas motorsports complex. it is a bit far for me; unfortunately i can't make regular trips to that one. i'm hoping the 60 and 330 ft will still show the difference.

 

I agree a great indication if you've lost any low down torque with the removal. Keep us updated

 

My 09 XKR has straight pipes. For me, it's the perfect level of sound. It's not too loud but you can definitely tell the car is on. Daily driver for 3 years now. No noticeable difference in power. Compliments everywhere I go.

 

I used the factory outside pipes to bypass muffler and replaced the stock tips.,,
even when you hit the dynamic mode button there is still muffling
going on the outside pipes still run thru part of the muffler and the tips themselves have resonator built in.
By routing exhuast to outside pipe but before the valve you get both of both worlds ,
wide open when you want and quieter when you dont. And NO it is not the same thing as pulling the 19 fuse,it is a LOT louder
trust me.. as you can see even the outside pipes go thru muffling material in the stock setup.

 

this is what I did, not the prettiest but no one is gonna crawl under my car so....

 

I like loud sometimes but sometimes I want quiet as well,,this is the best of both worlds.
You could even incorporate the switching valve into your aftermarket exhaust, one pipe with smaller muffler and one pipe straight thru,
really is dumb in my opinion to get rid of the choice.