Hello gang. I just bought my first Jag, an 1998 XJR, black on black. So far so good but I will be working on reliability and power mods soon. My first question is about the exhaust. It seems it has 4 mufflers and one or 2 cats, correct? Can anyone tell me the diameter and length of the mufflers and their intake and out diameters? I dont want to do a full cat back, I just want to replace at least 2 of the mufflers with appropriate Flowmaster or Magnaflow canister mufflers. Looking for some more grunt from the audio the car puts out now. I know its a beast lurking within, Id like to get some of that out in the open I installed a Magnaflow canister type glasspack on my Miata and it sounds fantastic. I just sold a Jeep Grand Cherokee on which I also installed a Flowmaster muffler and dual tips, and it sounded awesome. For the XJR, Id like to keep it all looking stock from behind the car as the stock tips are already dead sexy, but Id like to replace at least 2 of the mufflers for more sound.

Thanks in advance

 

My solution was to install electric exhaust cut outs. You can go from luxury car quiet to race car loud and anything in between with the push of a button and the cost is surprisingly low.

Lots of guys complain about "drone" on the highway from exhaust mods so be careful what you do to the stock system.

Deleting the "center" muffler or the rear "mufflers" or resonators as they are also called is also a popular mod.

More info on the cut outs here:
https://www.jaguarforums.com/forum/x...ut-outs-68743/

Pics of my install here:
https://www.jaguarforums.com/forum/x...ut-outs-71960/

Vector

 

Also, are the inlet and outlets centered or on one side or another?

 

Thanks for the quick response. When you say deleting the rear or mid mufflers, are you saying folks just replace them with straight pipes? That would be easy to do. How does that sound and do you know if it results in any loss of backpressure?

 

See install pic below, you can see where they are. Right behind the cats and centered, blowing out each side.

Delete the center muffler and replace with an X pipe. Remove the rear "resonators" and replace with straight pipes.

Backpressure? Jeeze! We have beat this horse to death already.

This exhaust mod is about sound and fun, not performance! If it doesn't make you smile and laugh out loud when you open the cut outs and put your foot in it then you should be driving a Prius anyway, lol.

I ran my XJR at Road Atlanta in November with the cut outs open all the way and did not notice any decrease in performance.

The factory system provides great performance, maybe a bit restricted over the rear axle, but if you want more HP go with a smaller supercharger pulley.
Vector

 

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Vector

 

Can anyone please tell me the diameter of the pipes? Im assuming theyre 2 inch all the way through. IS that right, are they bigger or do they get bigger at the end?

 

Vector's solution is the best of all world's. Great sound when you want it and no droning when you don't. If you read all the posts on various exhaust mods droning can be really fatiguing at certain RPM's.

 

And I can appreciate that setup, but Id rather take my car to my exhaust guy and just have some of the restrictive OEM equipment removed and custom fitted pipes welded in.

 

Have a look at AVOS on the XK8/XKR forum, he is getting north of 500 rwhp with the stock exhaust and manifolds, just sport cats.


So the stock system cannot be that restrictive.

 

I think they are 2" or 2 1/4" all the way through with some restrictive bends over the rear axle.

What everyone is trying to tell you is that if you just "take it to your exhaust guy" and ask him to remove some of the "restrictive OEM equipment" you may end up with louder sound than you want, droning at highway speeds, and/or an exhaust note that you don't like.

Most performance and sports car automakers spend a lot of time getting the exhaust note "right." They tune it with metal and market research to find out what level of volume and timbre the buyers will find appealing.

The initial development of the Mazda Miata is a great example of how much time and effort the manufacturer went through to make the car sound good to prospective buyers. The new Jaguar F Type is another. The exhaust note of the F Type is aggressive at WOT without being unpleasant at cruising speeds.

Unfortunately, our XJ's are luxury cars and that usually means "quiet" in the exhaust sound department. People in this auto purchase demographic pay a lot for quiet performance. A modern Rolls/Bentley/Mercedes is a good example of this type of quiet performance.

Rather than slap on a big and restrictive single muffler, Jag engineers fitted several components to the exhaust system to make sure the V8 could breath, but no one would be offended when you pulled up to the country club for dinner.

That is why I decided on the cut outs. It leaves the stock components in place, but lets me add a little sound or go to all out race car rumble and back to stock within a few seconds.
Vector