Hi Tad.

I dont know about the N6.0, but spi luff tension is critical on the Tornado. I would guess that luff tension is very important on the N6.0 as well.
With a slack luff, you would have to head up even higher than the I20 before you can start driving off..
If the luff (and foot/leech) is to long for the boat, you would probably be better off with a spi. designed for the boat (is your spi. designed for the N6.0?).