http://www.ft86club.com/forums/showthread.php?t=29923
http://www.ft86club.com/forums/showthread.php?t=20513
I own the N1 and have met up with several owners with the Evo 3. I think the final verdict is that the N1 is cheaper, not as loud and seems to be less prone to rusting. The EVO 3 is pricier, louder, and has already shown earlier rusting in the pipes.
Build quality appears to be very similar between the two.
The great thing about the EVO 3 is the piping diameter is 70mm vs 60mm, so some feel it is better if you have FI applications down the road.