Re: K&N 57i Induction Kit...
If I may add an opinion; panel filters are good but only if you oil them properly - better to use a standard filter than damage the engine with poor filtration.
Full intake to throttle intake kits do not take into account the helmholtz tuning of intakes that manufacturers may include in their production process. If you are going to remap completely then this may not be an issue, but otherwise it may well be imprtant with regard to low and midrange power.
I do think that removing some of the snorkels etc. after the filter box should not interfere with any helmholtz tuning and may help reduce restriction - but take care to avoid hot air intake and puddle water intake.
It is VERY hard to find out what manufacturers intended in the design of intakes as regards noise reduction, which you may not care about, and as regards tuning effects of intake design, which I think we should care about. But generally, leaving as much of the original intake as possible has the advantage of benfiting from the original tuners design. So, I generally start from the filter outwards, and leave the rest as standard.