if you want some quick HP, id deffinatley say go with forced induction. but if you got some money and want to stay NA, id go with an LS or GSR swap. They typically put out around the same amount of power if you put a 1.6 head on the LS and do the swap right. if it were me id go with the LS/vtec. it is alot cheaper to an extent. you will have to drill the block for vtec which isnt cheap and you ahve to take the internals out. they are both quick and around the same price if you have to get someone to swap it for you.
hope this helps at all