Modifying Exhaust centre section

[xjscharlie]

Hello Folks,
The centre section (combined silencer) on my XJ8 4.0L needs replacing & i thought of replacing it with just straight through pipes both sides. Wondered if anyone had done this or anything similar & what the results were?
Also has anyone put in a balance pipe between the two downcomers after the Cats of course.
Would be interested in anyone's experiences. Regards. Charlie.

[J44EAG]

The centre section on the 308 is no doubt similar to the 350.

I removed my 350R centre box completely. With it went an H-pipe balance pipe between OS and NS exhaust downpipes within the OE centre box.

My new set up dispensed with the centre box completely. In the space, a free flow X-pipe was substituted to help improve gas flow. This was hand built by Longlife Exhausts in Carshalton in Surrey. This modification was done at the same time as I had sports cats fitted. This combined with an ecu re-flash and ported and polished inlet system together with clearing an obstructive ridge under the throttle body. In addition, the throttle body elbow below the throttle was again opened out together with gas flowing the elbow and the supercharger inlet and outlets.

Noise from the exhaust increased just a little without being the noise headache that a modified S-type R exhaust caused on my 4 litre S-type.

Images of my 350R exhaust mod are here.

Mike K

[Orkney]

You could also try Roger Bywater at AJ6 Engineering in Cheshire, apart from AJ6’s and V12’s they also do a cat back stainless system for the V8 in both XK and XJ forms.

http://www.jagweb.com/aj6eng/exhaust5.php

Ian

[xjscharlie]

Many thanx~thats an interesting modification. Was thinking about a less elaborate modification than that but gives me something to go on. Regards. Charlie.