This may sound like a rookie question, but it is. I've read a ton trying to learn about different setups, but before I drop $500 I want to make sure I understand.

The CMYA M4 platforms use a QBS, Quick Change system to change springs. I assume that a different spring produces different FPS? For example, the M4 I'm looking at has a 400FPS Carbine Version, Vs a 350FPS version. Both seem identical except the barrel length and FPS. I assume that the Barrel length has nothing to do with FPS but the Spring is the only difference. I like the look of the 350, since it has a different color scheme, but want a little more power. Or am I overthinking it and the difference between 350 & 400 isnt a big deal?

This is the setup here...
https://www.evike.com/products/105534/