See an RBT/Police up ahead, close the valve & the car is quieter than my girlfriends hyundai.
works a treat -
but will still be a skyline, one look at the exhaust and its easily spotted and will then be tested with the valve open which I garuntee will be over 91db (I believe Joel's "wtf33" Natro was 103db when tested)
most of the people who say they are "shit", "Chinese crap", "valve fails", "overpriced" etc are either the ones who have never owned one, a jdm brand fanboy or were told on a forum they were junk -
have personal experience on both an sr20 and an LS1 in both instances open = raspy horribleness and when closed was quite simply on the worst sounds I've heard (think wet flatulence)
yes they are illegal, so is a lot of other things, a quiet car doesn't grab attention & doesn't sound "modded" -
its an NA skyline it won't sound modded because its not, save the money and build a decent system instead of trying to have the best of both worlds which in reality you end up with the best of nothing
Mate at the end of the day it's your choice, but IMO they're not worth the price (at all, especially on a NA)...