2003 Disco V8 exhaust upgrade

[DiscoDiver]

Has anyone upgraded their exhaust system from the cats back on the 4ltr V8?

I had a look under my 2003 V8 Disco and it looks ok until after the cats. The system from each side of the V8 looks like a decent size but after the cats where there join before the large muffler it goes from two 2inch (approx) pipes into just one 2 inch pipe.

I am thinking of a larger system from the cats back. Might improve my mileage and give a little bit more go????

Any advice appreciated.

Cheers Mark

[PhilipA]

I doubt if you will see much difference in fuel economy in normal driving.

The most cost effective performance increase is to change the muffler to a free flow type, and this on a non cat car will give an increase at high revs only. Maybe nothing on a cat car as usually the cats are the most restrictive part..
Newer cars have large volume mufflers which are relatively free flowing at light throttle and often have an even smaller diameter pipe inside to keep gas velocity up to reduce noise.
Also beware that it is very easy to get the dreaded "drone" with a large pipe and glasspack mufflers. I have fitted a Flowmaster lightly baffled muffler and a straight through dogleg resonator with an expansion chamber to my 92 3.9 and this gives a useful increase at high revs but no highway drone, and a nice "mouse" note at above idle.
Regards Philip A