Got rid of the overly restrictive over the rear end exhaust snakes in favor of these about as straight as it gets 2.25" pipes.

I had already deleted my resonators, so this was an easy mod. The shop only charged me $150 total

Since I don't go off roading in my Jag, the clearance is still fine.

The super tuned 1971 butt dyno says +2 hp.

As soon as I get my new 92 mm MAF wiring figured out I will be off to the same dyno I did my baseline on and will report back.

 

That is the approach used by the famous, but no longer available Macleod exhaust system for the XK series.

So, you now have original forward dual muffler and rearmost mufflers?

How is the sound?

 

Have tested this once on my car, but the dyno didn't reveal any results, all would fall in the error margin.

I don't think it is so restrictive either, and I still have the so called restrictive pipes and am able to push out more then 600 hp.

But maybe this mod makes it worth for the sound if that's better.

 

I thought for only USD $150 it wouldn't hurt to try. Marc B said he did this then got better milage.
I have the stock cats, stock center muffler and stock rears, I have only removed the 2 resonators, which I did some time ago.
The sound seems unchanged. I'd bet the farm this gave approx 2 hp, but agree on a dyno that may be within the margin of error. At any rate, at a total cost of only $150, it was worth doing just for the entertainment value.
I hope to have updated dyno results here in the next few weeks.

 

$150 is nothing so why not I would say, but I just wanted give my experience that its not worth for the horses as I didn't see any improvement on the dyno.

 

Agreed, I had read before that you tried with no clear large yield.

I wasn't expecting much, but I am curious to see if I get any increase in mileage as a bonus.

I figured for $150, even if it did not yield any HP, it would not hurt anything, but I would not have tried it for $1000.

 

Why not, Off road on a Jag would be hell of a Head turner,
I know i'd trip out if I saw a Jag off roading while i was on my ATV


But serious and all, Good info
Thanks for that +5 hp dyno proven for 150 bucks
how about the sound ? any changes there ?

 

Just to clarify, the +2 hp was my own organic butt dyno, not a real dyno. So it is not dyno proven.

The sound is slightly deeper and slightly louder, but only slightly. I do like it a bit better. To me the car seems to rev up a tiny bit faster, which is why I think it added a little power. When I was testing my alcohol injection, I felt about the same difference on the top end of the revs, where this is throughout the rev band. A real dyno showed the improvement with the alcohol/water injection at 7hp, so my butt dyno has some small amount of credibility (it is a rather small butt)