Engine Options for an 06 Matrix XR 5-Speed

Ok, my boyfriend just bought me a new toy. I'm already planning on a cold air intake and a new exaust system, but i want to know if there's more i can do to this thing. I'm pumped, but i've never really had a car i can mess with before. I'm open to all suggestions! the only catch? I can only use TRD parts unless i want to void my uber expensive warranty. Help me make my car more fun!

~Katie