No WAY would a custom turbo kit be as much as I/H/E.

Youre building one...you'll see how much of a pain in the ass it really is...its definitely not as easy as you think! There are tons of parts you'll need just to get a competent kit even fathomable to install. Then another bunch of parts you'll need to make it fit.

Then another bunch of sh*t you'll need to do to make it run. Then a whole lotta stuff to make it run with good power reliably.

Its nowhere in the same ballpark of a comparison.