I have 2 ground wires for my amp and distribution cap and they're about 3-4 feet long. Should I make it shorter or leave it?

 

Shorter is usually better (and neater). Before cutting, just be sure you will not want to move your ground to a further location in the future.

 

well if it ain't broke....

I would only cut them if they looked bad but if it's not causing any problems then don't worry about it...

And don't stress to much if you do decide to cut them and then move your stuff later, you can get new wires off ebay for less than a dollar a foot or you can get them at a local car audio place for about 2 dollars a foot. (no big deal if you talking about 3 or 4 feet)

 

Read the grounding sticky. Problems do not develop on the spot, they happen over time. Take the time to do what the sticky says and learn about how it can affect your system in your car. All cars are different, to treat them all with the same understanding though is a incorrect approach.