You say you want more power in the C3 - C5 range. That's a fairly broad range to want more power in. It's basically the entire pop range. You do have a fair command of your voice. If you want more power, it will most likely be found in strengthening your support. There were a few spots where you wandered off-key, but not bad for acapella. Again, strong support and pingy sound help to keep intonation from going off-course. Your highest notes distorted the mic a bit, and I think that's an indication that glottal compression would help you to keep your dynamics in a more controlled power band. You'll get the basics of glottal compression in Stage Three.
If you want to have a more pop sound, then you may want to start exercising with a lower passagio and working your head voice down as low as you can get it to go. Your highs did sound like chest, and you could have done those notes in a strong head or mixed sound for more of a pop or soul treatment.
Overall, I like the sound of your voice, and think you just need to decide what you want to do with it and go there. Ken recommends you first work your chest as high as you can, but he also leaves that decision up to you if that's not where you want to take your voice. Most rock/pop singers are going for that extended chest sound, and it takes a lot of work to attain. If you want high, chesty strength, you have to work the chest extension first, then go work the head voice after achieving the chest objectives.
Thanks for eveyone's help and comments.
Yes Scott is absolutely correct on Rocket's Red Glare. Even though you are pulling chest, it is strong and powerful and if you keep working this part of your voice correctly, you won't lose it, AND it will increase. (as you learn to create a mix voice you can make this sound smaller for a more poppy sound as well)
Also: Yes it's pitchy. Here is something to consider.
In much of the lower regster parts, you cover (or darken) the sound which makes it harder to hear pitch between your lower register and your upper register (this isn't the only problem but is a good point of consideration to start with). If you are more consistent with your tone it will help with your pitch. If you choose to stay with a darker timbre on the bottom, understand that this will sound right in your ear but actually be flat from a brighter timbral sound as you ascend.
Bob made some strong points as well.
You're on a good track.
Keep posting and learning, success wil come :-)