I am considering do a turbo K20 build and I have looked at a few of the kits out there and they seem expensive. Is it better to get a kit or just get all the parts and piece your own kit together?  

I hate to say it but the kit for these is better then if you werer to source parts. the k20 is a funny motor. DC had a hard time building a exhaust for these they couldn't get any gains from it, they finally did but it was very minimal