I'll tell you straight up. My buddy has a y7 w/ a z6 head thats got crower springs/retainer. Has 4-2-1 header, exhaust, intake, 7lb flywheel CC stage 2 obx 10mm wires with a tune from scotty at mainstream and still only put down 135 to the wheels. If you want 200 you gotta boost.

IMO.....Go with the y8 head and IM. get I/H/E. Maybe flywheel if you want all motor no boost, NGK wires and plugs small shot NO2 and Get a tune All motor on a budget.

If you got MULA $$$$$ Start talkin forged internal and shit!