In my oppinion, you can`t escape without doing some research on the web.
That is if you want you`re supra to be a "project" car. And I say that because u must buy parts from various providers, who make just a small part of car parts. For example U need an intake kit, go to K&N, for suspension to KW, etc.
You won`t find a site from where to buy all the performance parts you need, or, at leats, not one that can explain you haw a part will improve your car`s performance more than the same one from another supplier.
My advice is: You aither do some net research, or go to a tunning shop and let them do what they do best. Tune up your car.
A nice site for supra parts would be
www.suprastore.com
Hope to have helped you.