Both are intercooled, both are 8-9psi, the Kb is a 1.7l & the Saleen is a 1.6l. The main difference is the intake. Saleen's is too restrictive, KB has the better intake therefore will make more power.
Price mine is only $3500 2 months old with all papers,

If I had to do it again for a GT it would be a KB.