Boost by gear or not, good luck to you trying to lay down 600+whp in 4th gear on the street w/o a very large drag radial (235/60/15 MT), by the time you even get the boost up to that power level without roasting the tires will be out of gear...... LMK how that works out for you.

 

You should be looking into a Precision 6765 or an S366. Nice power you made, but that .63 housing is choking up top.