New or modified used GTI?

I have been researching various cars to replace my Toyota Tundra. The uncomfortable commuting days are over for me. It is time for something else. I have given little thought about cars in general for years. I cannot decide whether I should invest in a new or used VW GTI 4dr. A lower cost used model would leave room for immediate suspension and performance modifications. Doing so might crush a stock 2015 GTI I would imagine. Which choice do you believe is more wise? Should I spend less on a used VW? Would the newer model be better long-term as a base to build off of? Please forgive me if I am vague. Thanks for your valued opinions! :)

The older car is a very capable car but the new car is a better car. If you can afford the new car I'd probably pick it.