It does sound like it would meet the reqs of the motor, except that's for a TRX440, Your going to be looking for something like this:
"1987-04 WARRIOR
The Warrior kit works best with performance exhaust and open air box. Kit includes new manifold that moves carb closer to motor for increased horsepower without sacrificing low end torque.
Bore: 32x36mm oval
Thumb Kit #3011
Twist Kit #3150"
http://www.edelbrock.com/offroad/6-yamaha.shtml
You Want the warrior one. And it sounds like your willing to sink a significant amount of dough into the warrior. If so I'd ask some questions about the big bore kits, and look them up on here. There are a few members of the boards who work in atv/motorcycle shops, and from what I've heard from them, they generally lower the revving speed of the motors drastically, and also can make the warrior Much less reliable.
I'm only saying this stuff so you don't get something then a few months down the road think they are all shitty because the kit didn't work as well as FST makes them sound. There are other viable options that are less destructive on the warriors motor, such as high compression piston/cam combo, with a nitrous kit. With a set up like that you get the power when you want it, and the motor will still lug around since it has the stock bore, and is not as ready and willing to grenade on you.
Again, That is a Lot of work to be done to a warrior, Look at all of the viable options, and make sure you see it all from all sides, then make your decision.
Good Luck, and Welcome to the boards.
~Bill
p.s. a Link to the thread about us would be appreciated, if it's available. thanx