Anyone have experience with replacementof the factory XJS exhaust? I have found twocompanies (The Driven Man, Strebro) with replacement systems available. Was wondering how they might compare to having a custom exhaust made, both in price and performance.

Steve

 

I've got a 1996 xjs with the 6, and I am getting the intermediary mufflers replaced with some magnaflows, not sure how it's gonna turn out but I'll let you know. I'm not changing the piping because it's a tight fit and it's already decently piped.

 

Try Craigslist, Columbus Ohio. There was a guy in Zanesville trying to sell an aftermarket exhaust system for like an eternity, and I think I saw it still on there recently. If you see an ad for an XJS for sale in Zanesville, I think you found the same guy. I believe his car and parts were V12.

On a side note...my Dad graduated from PSU after after his WW II service. Guess who was an assistant football coach at the time? Yep, both of those old Lions are still around.

 

I have mixed feelings about full exhaust system kits, brought on mostly by the price tags. The one I've seen range from about $800-$1200.

Make friendly with a good exhaust shop and select some decent mufflers. I agree with Benito that the OEMpipes are sufficient, for most of us at least. I just think its a bit much to replace an entire system when 90% of any difference is gonna come from the mufflers themselves.

Of course, if the entire system in shot, that's a different story.

Cheers
DD

 

The stock system is in very good shape. The aftermarket system that I looked at was $1400. The main difference is that it's full 2.5"diameter piping. Also comes with "high flow" cats/mufflers. I want to be able to feel and hear a difference in performance from the V12!
There is a custom shop in the area that I am familiar with. I just don't know if the cost of having customworkdone would be equivalent in the end to just purchasing the system already fabricated.
How much does the size of the stock piping (2", I believe?)restrict the V12's performance? Are the rear resonators very restrictive?

 

I'm sure there's a lot of science to pipe diameter and I certainly am noteducated on the matter.

The rule of thumb I've gone by is that 2.5" pipe is needed with big engines....like 350 cubic inches, 400s, 455s, etc. In fact some of those big V8 guys to to 3" or more for the real hot rods.

Your V12 is 326 cubic inches. Personally I just don't think the bigger pipe is needed and it might even reduce the scavenging of the exhaust be end up being counter-productive.

Other will chime in.

I'm guessing a typical muffler shop can fix you up with four good quality low restriction mufflers for $500-$600 installed.

With the money you savehave them install an "H" pipe to bring out the true V12 sound.

Cheers
DD

 

Yes, I amone of those "big V8 guys" My Camaro is 346 c.i. and I run a 3" exhaust with a modified engine, my Corvette a stock 350 and I believe it also has 3" piping. I know that there is a risk of running exhaust "too big" for the motor, losing backpressure and reducing exhaust scavenging. I guessthe XJS boils down to2" of exhaustper 6 cylinders, which might be about right; technically though, I don't have proof or numbers.
Defintely want to usean "X" or "H" pipe in the system, both for sound and to equalize pressure between banks.
Again, what is the purpose of the XJS dual rear resonators, after the mufflers? Are they just to quiet the exhaust note? It doesn't seemthey would have an effect on emissions or anything else. Could I eliminate them altogether?

 

$1000 give or take isn't very reasonable in my opinion and this may not apply to you but here's why I decided what I did, when looking at the piping on my car 2.5 in is more than enough for me, also the bends in the stock system appear to be mandrel bent and not restricting flow in any sense whatever. For the V-12 2" pipes per bank isn't too bad, if it's mandrel bent, if it's pipe bent and gets all crimped around the turns then in my opinion I would replace it, if the it looks straight then just put in a good set of mufflers and it'll do plenty. On mine the rear mufflers were already straight through so they're just muffling not impeding so I decided to leave em so all I had done was have the first set of mufflers replaced with a set of straight through performance mufflers. And straight through is straight through so pick the muffler according to personal preference. The H pipe is a great idea, and any shop worth their salt can do it. Either way talk to a good shop before you drop a grand or more on a pre made system.

 

The main reason for them is noise. They are there to restrict the engine note to a nice quite sound. They put these on Land Rovers as well and we (land rover owners) chop these things off the first chance we get. It will make your Jag throatier but not overly. The route I've taken with the Range Rover is a flowmaster 60 series and resonator delete. In a few weeks I'm taking it down to the local exhaust shop and for about $115 they are going to weld the muffler in and bend a new tail pipe.

 

Thanks for the advice everyone, I guess it wouldn't hurt to talkto the local guy about the exhaust system before I buy anything. He's afellow car club member so I think he'll be willing to help me out.
I also found this quick link re: exhaust size while browsing for info: http://www.magnaflow.com/wideopen/performdata.asp

 

I just picked up my car with the new exhaust and it sounds great, sounds relatively stock while cruising around but gets a nice note to it when i stop on it, I used magnaflow mufflers.

 

Magnaflow is an excellent choice for exhaust components, I've had them on both of my V8s at some point.

 

Is the system hanging below the rear axle or is it fit like the oem.? I couldn't find any muffler that fit under the chassis in the same place as the OEM. I wound up having a custom muffler made.

 

no it's in the same exact spot, he ordered a muffler that is offset inlet, center outlet, which I know is not the same, and is like an inch longer than the stock muffler, but there was enough room where the hanger met the grommet to push the whole rear section (from the muffler back) about an inch or so and it all cleared and came out great

 

My car's in the shop as I type. The best replacement muffler we found was the Magnaflow p/n 11366 with an 11" casing, just as an FYI
I'm having two new Magnaflow converters installed and two of those mufflers. The resonators will be deleted and using 2.5" piping all around.

 

Hey Doug, the H pipe sounds like a great idea, as for the $500-$600 idea...............I went straight pipes, $0. for mufflers, $0. for catalytic converters, and then had my mechanic tweak the computer because of increased air flow, as I had a high efficiency air intake added.
Car runs like dream machine, and sounds like a small plane on takeoff when I am merging on the freeway.....................love it.

 

Hey, I'm a '98 Penn State grad too! Small world, there were probably only 40,000 of us at Bryce Jordan Center that day.