There's about 3 or 4 discussions on the board right now about the 1.6 vs. 1.7 rockers.
IMHO It just ain't worth it. Stay with the 1.6's. 1.7's add soo much strain on valve springs, push rods, lifters etc etc. I ran my combo through desktop dyno, and it came out to 579 HP @ 7000. Changed NOTHING but the lift (doing the math, and going to 1.6's) and it dropped all the way down to 576 HP @ 7000. This is going from an intake lift of .647 (1.7) to an intake lift of .609 (1.6)
I'll never feel 3 HP, and I'm sure that N2O plate will more than make up for it.
Do what you want, but in my opinion, in the long run it's just not worth the minimal gain you'll get. You'll get more for you dollar by throwing those stamped 1.6 hunks of recycled beer cans in the trash, and getting yourself a good set of 1.6 rollers.