It really depends on what you are doing. If you are a smaller framed person racing it on an MX track, suspension will make you faster with motor mods. If you are riding it in the trails engine mods and suspension will make you faster. If you are trying to drag race, get something else!
My blaster is bored and stroked with Vito's parts. It's snappy and nimble but will never be fast at the drag strip. It has been a great machine to teach my kids to ride while still doing just fine with them on it in the sandy trails and dunes where more power is needed. You put my 200+ lb ass on it, its not real impressive at the dunes, but is still fun to ride on hard pack.
Start with The airbox like stated before, get a clamp on filter adapter, the lid on the box is restrictive. Get a pipe on it, most Blaster pipes will yield the same results.
Just be careful as stated before and weigh your options. If you are a bigger guy trying to keep up with banshees, your money is better thrown at a banshee.
You WILL outgrow the blaster no matter how old or big you are right now.
01' Raptor 720, Stage 2, FCR'd
97' 250 Vitos Blaster
06' Rhino 450
94' Banshee T-5's, Vforce, ported, Cool Head, 2-1
06' Wolverine 450 - Stock!
06' LTZ 440
94' Vmax4 750, 96' 600 MountainMax, 07' Nytro(b00sTed)
06' Vmax 1200