Hey mate not sure if you have seen my posts on my d40 but we have had it on the dyno a lot and have tested a lot of things.
First off let me say I have not actually tried the k@n cold air system but I have got a k&n and have slightly modified my factory airbox.
I know the k&n cold air system WILL go up to a safari snorkel but not sure about others. And they will be loud.
I actually used some of the flexible conduit (like in your pic) from the factory airbox to the inner guard and it was very loud just like that.
Now to my point about the dyno.... During a couple of different runs we have tried lifting the airbox lid all together and saw no gains at all.
Also we have measured vacuum from just after the airbox and found there to be very little restriction. What this all means is that apart from a heap of extra noise you probably wont gain much other than a hole in your wallet.
I run a k&n but don't do much if any dirt road stuff. Pretty sure from memory that even though the poms claim up to 10kw from running a k&n we saw nothing on the dyno initially. That is not to say that the engine wont learn over time.
You will get the usual people tell you that k&n's let dirt through etc but I have found in my experience that this may be due to poor fitment by owners rather than thru the actual filter. JMO though. Stories of maf sensors failing are bullshit too.
After all that I would say if you feel like spending a couple of bucks go the k&n panel filter and leave the cold air system alone unless ya got money to burn. If you expect big gains I would spend somewhere else.
Hope that helps.
Regards
Brian
