Intakes are always a heated topic of debate that is mostly just theoretical speculation. In practice it doesn't make much difference as long as you ditch the stock setup. I have a '98 and it is the same intake wise as a '97. '97-'98s have a horrible stock intake, so anything will be an improvement. You also need to keep in mind that the more aggressive your setup, the more of a difference an aftermarket intake will make. Most people that only mod to a 3.4 pulley don't need a whole lot to feed it adequately. Once you start running 11 seconds in the 1/4 you might need to be more choosy.
I have a Wizaired that is just taking the winter off, but it is a good box. I'm not a fan of the flexible tube and so I am doing something else there. But, you really don't need to spend that much. I always encourage people to do a DIY FWI. You'll get the whole 5hp you can hope to gain from an intake and save a lot of money. For some, aesthetics are important and don't like the DIY feel, so you need to decide what is important to you. Between the Wiz and Thrasher, I've read that the Thrasher's intake tube is smaller than 4" (3.5" I think) while the Wiz has a true 4" tube. Again, probably not going to make a big difference until you are heavily modded.
Yeah you have to deal with the coolant bottle crap. There is no kit per se, you just get from a dealer, or vendor, the GM coolant bottle from a '99+ GP and mount it to the passenger side strut tower.
