Hi bud,
None of the exhaust systems will affect your Mot - most attach from the 'Cat' back or the 'Y pipe' back.
Switching your standard cats for 'Decats/test pipes' is the only time it will affect your Mot due to failing emissions.
Have a look below, if you click the exhaust section it will show you all the exhausts available.
Any questions or help required give me a shout, always happy to help
http://www.tarmacsportz.co.uk/350z-exhaust-parts.aspx