Hi, I am a relativley new member and I have been trying to find some information about how to improve the exhaust system on a 1998 (4.0) Plus 8.

Is it possibly simply to remove the Lambda sensor and remap the engine? If that is so would I have to undo this again prior to every MOT test? I would also like to fit a new set of free flow manifolds and exhaust system. Are there any good and reasonable suppliers of these?
Thanks.
Christen