hey i have a 99 avenger w/ a 420a 4 cyl and i was considering getting a 3.0 swap and was quickly convinced that that wasnt the answer to my HP problems ive decided to put a hahn turbo system on my car after having the motor rebuilt but my real question is how much computer work is involved in putting on a turbo i know how to install everything but i dont know how to hook the turbo up to the turbo any suggestions or should i leave it to a proffessional?????

 

The computer question isn't really a big deal (yes it is but not in this context), air/fuel tuning is what you'll need and that isn't a real issue because there are products that fill that void. Contact Hahn or look at their stie for the Avenger again and you'll see that they have everything you'll need for their "Stage I & II kits"
I would also leave it to the pro's if you feel lost in the installation. It is a good time to learn, but it's really not something you want to mess up at the start because then you'll have issues all throughout and you'll just want to get rid of it then, lol.
I would let a shop that is familiar with turbo cars do the install, since you're thinking about the Hahn kit and getting the motor rebuilt (good idea btw) just to be on the safe and happy side.