who has done this? is it a good cheap mod to do to the 88-91 civics?
d15b2 block with the d16a6 intake mani/ injectors/resistor box/wiring and ecu.
does it gain pretty good amount of horsepower? and how much money is it? i dont really want to motor swap it. any input will be appreciated thank you in advance

 

I have done this swap, it made my CRX feel more responsive and fun to drive. I got the parts from a complete motor and transmission from a guy who had wrecked his CRX for $100. The motor is a JDM D15B VTEC that he put his SI parts on with a RPM activator, I'm in the process of building the D15B back to the way it should be.
Don't forget that you will also need an SI distributor to go with the items that you listed. In my opinion it is worth it to do this swap and save for motor swap later (always upgrade).