I'm no expert on Honda engines but when it comes to most NA 4 cylinder Toyota engines its pretty hard/expensive to make much power. Your average Bigport 4age will make about 70-75Kw at the wheels upping this to anything over 100kw is extremely hard/time consuming.
Another NA engine conversion people do is the BEAMS 3sge i thing from memory with a nice tune an exhaust these put out about 130-140kw, but this conversion is very expensive.
If you want to make pretty good power with the ability to make good power your probably going to have to go turbo. Your best bet IMO would be to go for a 3sgte, the later generation engines are pretty solid and its quite easy to extract power from these with just a few simple bolt ons. In terms of legality depending on what state your in as long as you do the work properly your shouldn't have any trouble getting the car engineered.