I ran a gt30/71 on my Sapphire on a standard engine that had been rebuilt a few thousand miles previously, have to say it didn’t last very long, the engine let go during a live road map and upon strip down there was milk at the back of the engine where the head bolts to the block.

Prior to the live map when I had fitted a few more spangly bits chasing more horse power the car ran 420 bhp with 400 ft/lbs torque. It had switchable maps low boost 15 psi high 30 psi.

if you are chasing big horse power 400+ you’ll definitely need a decent rebuild with long studs imo