I have a new z and just installed a r4 pipe , pro flow adapter and a kn filter I installed a 160 main that come with the pipe and it ran really well with out the air box lid. But I do not really want to do this due to the riding conditions I ride in, next I tryed a 145 and it runs ok with the lid but lack the power I would like to have.I have installed some of the new air box vents that white brothers ahs out and it seemed to help a little, and what about the snorkel it just seems like it will let alot of dirt and water in the air box I could really use some help any suggestions would be appreciated.

 

yuo should run it witth the lid off or atleast the snorkel off. The airbox most restrictive part of the Z400. You wont get as much as of a noticeable gain running with the airbox lid on. With the pipe it gets the air out faster, now you have to get it in faster to see performance gains you are looking for. Just imo though.