If you can't put down what you got, then you ain't got nothing. 373s are good for stock to mild bolt ons. I bought mine with 373s and am about to go FI in a week or so and kinda wish I had 355s instead. 1st is damn short in mine stock so I can't imagine with 600whp. 410s will give you higher RPM on the highway and a lil less mpg as well if that means anything to you. Most people think 410s and they think faster but not in this case, especially for FI 6spd manuals.