Got the mufflers and x-pipe installed. Sound great on full throttle or above like 3K, but I feel like the lack of back pressure makes it a dog down low and it really drones. In addition to that, it feels like the transmission goes through the gears to quick; like I am at 30 mph and in 5 gear. Have to use the flappies much more than I ever did.

Any ideas or tips? I may go back to stock... :-(

 

That doesn't sound good....You have the 4.2 non-supercharged, correct?

 

Yes correct. It could be the transmission was always in the gears they are now, but I did not notice as much. I have to drive XK more like I did my S2000; keeping the rev's higher... Will give it a couple of weeks and if not any better, will buy a used OEM exhaust. I don't want the old one re-welded.

 

That's the same one I have as well. I was contemplating that same idea but I was afraid that very thing would happen. I have no experience with car exhausts but, I work on motorcycles quite a bit and what you described is exactly what happens when you install a larger, more free-flowing pipe, without remapping. It's probably running a bit on the rich side.

 

I kept the same size pipes too. Oh well...

 

That's interesting. I think you are right about not noticing a quiet car shifting....probably shifting the same but with out noise you wouldn't know it. I'm kinda surprised about the back pressure loss. You still have the stock Cats and mufflers in the back for back pressure. I have stock Cats and retained the single resonator but have no muffler at all. I wondered if I loss some low end, but it could be the sound thing playing tricks again.
I don't have any drone that I really notice, but i'm not on the freeway for long periods like you mainland folks.
Are you going to put the stock muffler on after cutting it open to permanently route it out the noisy side??? While leaving the X=pipe.

 

Plan is to go back 100% OEM. Debating whether to leave the x-pipe on actually. I know the stock system works right. Why I 2nd guessed Jaguar has made me the fool and lightened my wallet.

 

Do you like the new sound???

 

When above the droning range, yes I do like the sound. Gets too boomy down low. Throttle "feels" lighter.

 

I like that, I'll be looking for details!

 

Straight pipes are a good thought, but whatever you do dont go to 2.5" pipes like I did.
you wont get enough back pressure, even though it sounds great.
If you go back to one of my posts in january of this year you can see a system I designed and had built with magnaflow collectors going to 2 round tips.
Looks just like stock. I had to put motorcycle baffles in the pipes to get the back pressure. I was lucky and got no drone

 

 

Reverting back to OEM on Thursday.

 

Not sure if the same theory will apply, but V8 BMW M3 owners have been doing a modification to the stock rear muffler for a while now, which involves cutting it open, removing the fibreglass padding from inside, welding tubing on to the pipe sections with perforations in (if any, in the XK's case, not sure) and closing and welding the box up again. Those that have done it seem pleased with it, could be worth thinking about?

I've got a 4.2 XKR, I changed my middle section for a Spires stage 1 section which takes out the center silencers and replaces them with an X-pipe. I get no unpleasant drone and it's only really any louder than stock when giving it some on the throttle. I haven't noticed any negative effect on performance either.

 

Yikes all that trouble going back to stock. Just do something while you're in there, like force it through the by pass side some how. Like weld the flap open?
I know you're after some sort of sound! Like the Maserati GT! Wink

 

I'm very conflicted about my XKR's stock exhaust. I love the sound. I just want it to be maybe 30% louder. I have already removed fuse 19. Why did they make it so darn quiet?

 

I am considering doing the x-pipe instead of resonator, but will I be in the same situation of not enough back pressure?

 

Bighenderson
Is that your car in the video? Sounds great! Really like a wild animal. Nicely set up. More pic please!

 

I would link so. You still have the cats and big main muffler in the back. Should just sound a little louder.

 

The XKR-S stock has no pre-resonators, just an X pipe and when the valves are open it is straight through except that the exhaust pipe is bend in an S shape in the rear muffler.