What?!? When did I get drugged and dragged to Vegas, cuz I can't remember any such ceremony!!

PS - I'm not married, never been. Girl test is on, now...which one?

GreenJ, i'll do my best to thoroughly document/record before and after x-pipe installation sounds.

 

I unintentionally did the girl test in my '87 Mercury Cougar (5.0L V8, headers, no X/H pipe, 2.25" mandrel bend side exit, no catalytic converters, glasspacked mufflers) I drove with the windows down but very sedately. Almost immediately I got "Is there something wrong with your car? I think you have a hole in the muffler." When I told her that's the way it was supposed to be, she wanted to hear the car at WOT, so I obliged She was half scared, half happy, and no longer wanted to ride with me...until the next day.

I'm curious how the final project sounds too. I'm not going to make the Jag anywhere near as loud or raw as the Cougar, but it is just too quiet right now. I'm going to talk to my exhaust guy next Tuesday and bounce a few ideas off of him and see how much he would charge to do a few things and we will see what happens. I'll be sure to do some before/after videos if I decided to proceed.

 

In order for it to be a valid, and objective test, why, all of them of course!

Look forward to your notes.

 

Sorry Matt, mea culpa. I saw some of your pictures a while back and assumed that the females in them were your immediate family. I guess I slightly skewed your Family Tree! Let the "Girl Tests" begin................and...........watch out world!
Brian

 

No problem Brian

Got the x-pipe installed this morning, and drove straight to work on the freeway, not alot of time to 'listen' to it. Tonight I'll do more observations.

BTW, my muffler guy says the XK8 has 2" diameter pipes all the way back from the cats. Had to go adapters to get the 2.5" x-pipe installed.

I'll follow up after tonight/tomorrows videos and drive tests.

 

My understanding is that they are 2.25" pipes. Anyone else?

 

I don't trust that number either, I'll check circumference and see what the DIA truly is.

 

I originally did the very same thing and found that it did not sound right and that the car felt as if it was down on power. After some quick investigating, I was informed that the loss of compression from the cats to the rear mufflers was the problem(I have a Mina exhaust system). I instantly ordered the Magna Flow crossover pipe and had it installed. I had it put as far forward as possible. That was a major improvment for my set-up. Can anyone confirm that the loss of compression from the cats to the mufflers makes a difference not only in sound but in preformance. I am no expert but I can say that it sure seems that way to me. I did go with the 2.25 diameter pipe from Magna flow on the crossover and my exhaust guy did do a small modification for the 4 pipes to fit. Zero issues and lots of compliments.

 

OK, I took the plunge a couple of days ago and cut the main muffler out of my XKR, same as a couple of you have done. There was no 'Y' or 'X' pipe between the sides

Here's the report (at least according to my ears).
Idle is a bit louder, not much.
Hwy is identical at cruise.
Stand on it and as soon as it gets above 3000rpm, it lets out an onholy deep growl you wouldn't believe.

Only problem was that below 3000 with the driver's window down, it sounded like a plug was misfiring since you really only hear one bank well. Windows up it was not really noticable.

Soooo, I took a piece of pipe and fishmouthed both ends to weld between the two new pipes to form an 'H'. The result is very similar to a quiet version of my 2000 GT Mustang but very deep. A small (satisfying) bit of idling rumble at idle or cruise. Not very loud on gentle acelleration but as soon as you get on it the sound is deep, powerful and fairly loud.

Hope that helps.

BTW, no noticable loss of power. I end up breaking loose more but I think that's because I'm enjoying the sound.

 

I totally agree RJAG with all points above, the H is similar in nature to the X-pipe, balances out those exhaust pressure (pulses) so its even.

Center mufflers will be falling from many owners after our observations, I believe.

I also saw my average MPG drop quite a bit after a week with the new arrangement (and lovely sound)..but I totally blame myself for the heavier right paw.

 

The diameter of the stock piping is between 1 7/8" and 2" in most places. The bend where it goes over the axle is only 1 5/8" !!!

 

Well, after listening to it in the drive and tooling around the neighborhood, with the center muffler out, and the x-pipe in, the tone is the same low grumble, but the volume of the note has been reduced by 30-40% I would estimate using these flaps on the side of my head. I wish I had just kept the straight pipes on there, sounded grumpier, but not overly rude.

I suppose I may have lost some volume by using the 2.5" x-pipe...had I used the 2.25", perhaps i would have kept some of it, though I can't explain it totally.

Some vids of before and after the x-pipe install. The first - no center muffler, straight pipes. then two more stock silencers each side.


2nd, x-pipe installed where center muffler was, same stock silencers (2 each) to the rear.

 

Thread merged with the other "Sounds Much Better" thread by Thomasso, hope everyone doesn't mind...same stuff, I hated going back and forth. so yes, I did it for me.

 

I'm under the impression that the X pipe is going to quiet your exhaust a little.

Here's an article that was sent to me on another forum:

An x-pipe balances the exhaust pulses and improves scavenging.

Here's a clip from Magnaflow that explains it:

For any performance exhaust system, some type of crossover connecting the two sides of a dual exhaust system is important because it acts to balance the two banks of the engine. The common H-style crossover is good at balancing sound pulses between the two halves, but does little to promote scavenging because the exhaust gases tend to follow the path of least resistance, which is straight through each pipe rather than taking the 90-degree turn through the H-pipe into the other half of the system. In an X-pipe system, however, where the two sides of the system intersect, the gasses have no choice but to intermingle as they pass through the junction. This promotes improved scavenging effects by smoothing out uneven exhaust pulses from the engine’s firing order. It also helps quiet down the exhaust, resulting in a mellower, less raspy tone. The faster acceleration of the gasses through an X-pipe causes them to flow in a linear fashion parallel to the walls of the tubing rather than tumbling. This “laminar” flowing gas is much quieter than tumbling gas, resulting in an exhaust tone up to 8 decibels quieter than a traditional H-pipe.

Let us know how things work out for you.

 

So, you're saying if I want a 'stable' exhaust note, but keep it loud, I need the H?

Figures...

 

The question is what do you have going on after your "X"- pipe? (sorry if you've mentioned it before I haven't kept up)

If you have retained the stock rear section there are a few things you can do, like removing the rear silencers near the tips. (that was my first mod even with leaving the other sections in tact it it increased the volume a noticeable level)

The portion with the resonators that bends over the axle is very restrictive as noted on an earlier post the pipe diameter was decreased, in fact the OE section on my car transitioned to a flattened oval shape for a portion.

 

Correct Marc, everything is stock after the x-pipe, including two silencers per side. Before I chop anything else off, I think I'll drive it for awhile, I think I was just used to the straight pipes for that one week, and favored the tone and volume it created. Its just quieter now, but I can still hear it. That is all I was looking for anyway.

I'll consider that rear silencer next. Thanks!

 

I'm an old hot rodder from the 50's and 60s. I like my exhaust to "Rap" As we called the sound. H's and X's although im sure make a slight improvement in performance also take the rap out of the exhaust and make it more of a throaty roar. Each to his own. On the subject of large exhaust. A V8 Jaj is only 4L about 250 CU. With the exhaust already choked by the CATS a larger exhaust will give very little performance boost. Thomasso

 

Matt,
This sounds exactly like what I am looking for. So what size X-pipe should I get? The 2.25"??

 

Lew, if I were to do it again, I'd get the 2.25". Then again, I'd also do the H-pipe.