I'm about to ink a deal on a new hybridish bike. I've been thinking about some things I can do first to make it more comfortable. Yes, I'm going to ride the heck out of it before I go upgrade crazy but I was just wondering how much bang for my buck I get with some carbon upgrades/changes? I'm eyeballing new handlebars, stem and seat post. Are they worth the change from alloy for the comfort and weight savings? I'm looking at about an 75/25 mix of pavement and light trails.

Thanks for any advice.