First of all, he gave you a lot of answers to your question.
If you're given every answer for free, you will not retain it or learn it, you will only take in the answer at face value. If you do research and learn the physics/mechanics/engineering etc. yourself, not only will you have the superficial answer, but you will understand
how and
why.
A great online tool that I always use is
www.howstuffworks.com.
If the manifold won't fit your car, or if it's a crappy design it's not worth it. If the 18g is beat to shit, it's not worth it. In general, you could probably get that setup for $500-$600.
You will also need to tap an oil feed line, get all the piping, get a properly-sized blow-off valve, get a properly-sized wastegate if your friend isn't including one, and get AT LEAST a wideband air/fuel ratio meter+gauge &
a piggyback fuel controller for tuning. I
highly suggest getting a chipped ecu and tuning with Crome, or getting a Hondata S300. If you really want to go all-out you can get a standalone ecu like the AEM EMS.
The most important part of a build - especially a turbo build - is the tune. Making sure your air fuel mixture is at the proper levels (fuel map) at the proper times (timing & timing map) is the only way to ensure your car is functioning properly and will last.
www.PGMFI.org as well as some of the users on here are excellent resources for tuning questions.
But first, go to
www.Howstuffworks.com and find out how a turbo system functions, because judging by your posts (and I'm not trying to be mean when I say this) you don't know what you're doing. But don't worry, I've been at this for a few years and I still have plenty of stuff to learn as well. It's an ever-evolving learning process
Good luck man :thumbs up