Figured I'd clarify cause I installed one Friday night after reading this post. I'm a noob. Def worth $40 to save the radiator, I've replaced them in cars and they are a pain in the ass so easy choice. Just making sure I wasn't missing something based on the comment. It wasn't clear based on the comment if I was missing some reason why I shouldn't have done thatFull exhaust = Wanted to fine tune the look, sound, and performance. Mission accomplished.
Power Commander V = You must have missed where I said I plan on getting my motorcycle dyno tuned. Also, I wanted the ability to adjust parameters you normally cannot. With the Akrapovic map, the Ninja 400 runs better and faster than a stock and "zero" map (which, as you know, is basically like no PCV installed). The first question dyno tuners here in Illinois have asked me is, "Do I have a Power Commander installed?"
I have also fine tuned the exhaust so it pops less (by modifying the lower RPM range). So far it has been an originally "iffy" upgrade that has helped my motorcycle run better than just the Delkevic and stock ECU. It will pay off further when at the end of this month I get it dyno tuned.
I have a 2021 Ninja 400 ABS, so ECU tuning is so far limited. I would like to eventually do both. Also, considering the bike in stock form runs lean from the factory in the mid RPM range and rich in the high RPM range, now it runs better and less lean or rich in the respective place. The full exhaust definitely made the bike run leaner than the factory exhaust, due to increased air and the headers breathing much better.
AIS block off kit: Removing this has stopped a lot of the popping (due to introducing more air in the system, which the full exhaust system already does) and will be better when I get it dyno tuned (it throws off the Air fuel ratio and makes it read inaccurate)
Risk versus reward, either install a radiator guard, or happily drain your coolant line and replace a not so cheap aluminum radiator when, eventually, you run over rocks or sticks and they plunge into your radiator and it leaks or looks like crap.
No need to pay a ton for one, but silly not to have one in my opinion. It weighs nothing, cheap, and the provisions are there.