astra air filter

Hey guys, this is my first post. At the moment I'm really interested in trying to come across pros and cons of both a stainless steel air intake pipe or a silicone one. purely to get the noise of the B.o.v, so which is best? been to a garage that was recommended to me for custom exhaust systems...

Changed the air filter, the MANN filter has the normal folder paper element but also has a foam type material glued to the paper element. Air passes thru this first. I assume this is standard & I don't need to remove this (protection for shipping)? Other air filers I've used for other cars...