Well, the heads that come with the Imperialstar are garbage. But you can't just get new heads and expect them to sound good. You need to know how to tune, a topic that has been discussed to death here (use the search function to see
) and numerous other places on the internet. If you are just starting out tuning then I think you might benefit from the relative ease of tuning pre-muffled heads (like Pinstripes, EC2s, etc.). However, make sure you get new resonant side (the bottom side) heads for all of your drums too! They are arguably more important to good tone than batter heads.
Since you requested Evans, and it's 1 am here, I'll just give you a table of a very general purpose set of Evans heads with EC2s. Don't forget Remo and Aquarian though!
Snare: Coated G1 (average), Coated Power Center Reverse Dot (more 'pop'), Coated G2 (thicker), or EC Reverse Dot (thickest) batter head with a Hazy 300 resonant side
Toms: Clear EC2 batter heads with Clear G1 resonant
Kick: Clear EMAD (very easy to tune but very limited in options as well, for more versatility, get an EQ4) or Clear EQ4 batter side with a black EQ3 Resonant resonant head
Hope this helps.