Get a blower that give you growing room. By the time it is installed and tuned, you will know [exactly] what the next weakest link in the chain is whether that's gears, exhaust, heads, what have you.
Make sure the engine is in good shape, install the blower, make it right, then go from there. It can be a big chunk at once it's better than wasting money and time on junk mods you'll have to 'undo' later for even more money.