Downpipe change...will I need a remap?

[andysmee]

As the title suggests, I am about to replace my stock downpipe with a nice SMB 3.5" to 3" stainless one. I am also replacing the Blitz Nur Spec backbox for an SMB twin tip silencer.
 
Do I need to get a remap? is there any risk of running lean if I don\'t?
 
Any advice?
 
Andy

[shaunwil]

More chances of boost spikes with free flowing exhaust system. A remap would be a good thing to get ! May only be on the dyno for an hr at most sorting it out so not too expensive !

Shaun