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I would assume their function is to do both. Has anyone deleted them and run straight pipes (no X ) to the back box and if so what results did they have with noise and resonance/drone.
From my experience with my 4.2 XKR, 90% (if not more) of the drone component was due to my (stupid) removal of the stock rear muffler. It all went to hell after that. I had both of the resonators deleted and an X installed on it, and still no drone. I removed the stock rear muffler and replaced with non-chambered Borla's, and the dreaded drone raised its ugly head. I would assume that this would be the same result with my 5.0 XKR. From my past experience with other cars that I have also done exhaust mods, the drone seems to be a result of the main muffler switch to aftermarket. I can't tolerate drone at any level. It's the worst! As the XKRS has zero resonators/mini mufflers before the big rear muffler, I think it is safe to assume that no drone will be caused by removal of the two resonators/mini mufflers on my XKR. If anything, it seems as if the XKR rear muffler is even more sound and drone suppressive than the XKRS's.
Read my build thread, page 3 starts the exhaust which took a couple tries to get where I want it. Page 21 starts the discussion about Helmholtz resonators. Currently it's 95% there. I do get some resonance when it's close to freezing because the speed of sound changes enough when cold that my resonators are out of 'tune'. As goofy as my rear box looks it still weighs a lot less than the stock //R box. Outer tips are short resonators, inner tips have chambered mufflers with fiberglass wrap and the boxes are Helmholtz resonators to kill the killer drone I had. Really, really good sound.
Pic of the inside of the stock front mid pipe resonator from my //R. Just a series of slots cut in each pipe at different locations to tame some tonal issues. I don't think there's any packing between the pipes.
Before the resonators I ran up to Allentown to pick up a stock //R box and the drone about whooped me. Stock box on was mind numbingly boring, like driving a pickup it was so quiet. Helmholtz killed the drone but left enough tone to enjoy the ride.
The XKR-S/PAE centre pipe has the same 55mm OD tubes as the regular XKR, and the same as the 4.2 as well.
There is zero drone on my XKR, none whatsoever. 400 cell cats, straight pipes with x-pipe, stock rear muffler, and the active exhaust still functional.
It's quiet as a mouse when cruising and screams when you've got your foot in it.
I can't speak for the 4.2 or the non PAE exhaust but as for the 5.0 with the PAE all I know is with the top down and in a tunnel the sound blows you out to the point where you need to back off to regain your hearing. I'm more then happy with that. From calm to chaos .
On the 4.2 //R while the cut outs are a great concept I think the corporate legal folks tamed the exhaust too much across the board. Once Ford left go and the state of the industry became more performance oriented the better sounding exhaust became acceptable.
There is zero drone on my XKR, none whatsoever. 400 cell cats, straight pipes with x-pipe, stock rear muffler, and the active exhaust still functional.
It's quiet as a mouse when cruising and screams when you've got your foot in it.
love it. that is exactly what I will be doing, except for 200 cell cats like my old 4.2 had (frickenfast). love that there is zero drone as long as the stock rear muffler is on. it's crazy heavy, but oh well.
Read my build thread, page 3 starts the exhaust which took a couple tries to get where I want it. Page 21 starts the discussion about Helmholtz resonators. Currently it's 95% there. I do get some resonance when it's close to freezing because the speed of sound changes enough when cold that my resonators are out of 'tune'. As goofy as my rear box looks it still weighs a lot less than the stock //R box. Outer tips are short resonators, inner tips have chambered mufflers with fiberglass wrap and the boxes are Helmholtz resonators to kill the killer drone I had. Really, really good sound.
Pic of the inside of the stock front mid pipe resonator from my //R. Just a series of slots cut in each pipe at different locations to tame some tonal issues. I don't think there's any packing between the pipes.
Before the resonators I ran up to Allentown to pick up a stock //R box and the drone about whooped me. Stock box on was mind numbingly boring, like driving a pickup it was so quiet. Helmholtz killed the drone but left enough tone to enjoy the ride.
There is zero drone on my XKR, none whatsoever. 400 cell cats, straight pipes with x-pipe, stock rear muffler, and the active exhaust still functional.
It's quiet as a mouse when cruising and screams when you've got your foot in it.
I was told that the 4.2's had 2.25" pipes and the 5.0's has 2.50" pipes. did they not step the 5.0's up to 2.50"? glad I didn't order this yet. they make it in a 2.25" as well....
I was told that the 4.2's had 2.25" pipes and the 5.0's has 2.50" pipes. did they not step the 5.0's up to 2.50"? glad I didn't order this yet. they make it in a 2.25" as well....
I was told that the 4.2's had 2.25" pipes and the 5.0's has 2.50" pipes. did they not step the 5.0's up to 2.50"? glad I didn't order this yet. they make it in a 2.25" as well....
This is my 07 XKR with Magnaflow 59975 High-Flow Catalytic Converters and fuse 19 out. The rest of the exhaust is stock. I found it slightly too hooligan with fuse 19 out so I put it back in when I got the cats put on.
As the exhaust valves open on the overrun I learnt to play with the accelerator around town to get the most out of the sound. In comparison my new 2010 XKR sounds so quiet!
I've no backbox whatsoever and the car's still a pleasure to drive at all speeds...yes it is loud, but nowhere near as loud as my XK8 with no cats and straight through pipes...so it depends on what you're use to.
What I don't understand is why I get more burble/pops/bangs in dynamic when my air pumps are capped off??
Has anyone actually weighed the backbox itself as would love to know how much weight I'm saving Am only guessing at between 35-50lbs?
May you can help me. I am confused about the numbers on the rear muffler. Does the XKR rear muffler has: 9W83-5K244-AB 2QGA and the XKR-S or XKR Peformance rear muffler has: BW83-5K244-AB 3GGA
May you can help me. I am confused about the numbers on the rear muffler. Does the XKR rear muffler has: 9W83-5K244-AB 2QGA and the XKR-S or XKR Peformance rear muffler has: BW83-5K244-AB 3GGA