Themostat and any hoses under the manifold would be a good idea to change and of course the intake gaskets. It is also a good time to change the main serpentine belt if you have not done so in the previous 12-18 months as it will be off during the install and is behind the SC belt - I recommend the Gatorback belt - p/n has been posted several times previously.

Some installers have experienced cutting of the injector o-rings so having spares on hand might be wise. I have installed over a half dozen kits and never cut one.

Depending on your mileage, other items might should be done at the same time - see your owners manual for factory recommendations. I would also recommend changing to synthetics if you have not already done so.